Two years ago I was nervous and excited. We’d just sent the first palettes of Urban Garden Magazine to grow stores around North America. How were they going to go down with retailers and growers? Would they love it, hate it, treasure it, or trash it? Not only had we put everything on the line to get things off the ground, but we’d worked night and day for months to get to this point. Finally it was crunch time.

I’ll never forget the day when the phones started ringing and emails began to flood into our inboxes. The feedback was clear. People thought we were a little crazy, but in a good way. And they certainly appreciated the growing advice—big time! Urban Garden Magazine was an overnight success!

Phew! We knew it all along—why of course we did! (Ahem!)

Since then, I don’t mind telling you, it’s been one hell of a learning curve—building room after room for testing products, sourcing info, answering queries, meeting experts in plant lighting, HVAC, plant physiology, entomology, irrigation, growth media, my head nearly exploded on several occasions. The challenge of keeping up with the latest innovations in indoor gardening needed to be met on a near-daily basis. But it’s all good, and our office hasn’t stopped buzzing since day one.

You’ll have no doubt noticed the “Grower Day” feature on this issue’s cover and maybe you’re wondering what it’s all about. Let me tell you straight up. Grower Day is a meeting of the finest growing minds in the world combined with an exhibition of the most cutting-edge and innovative growing equipment you’ve ever seen—all in one place. So if you’re as passionate about growing as we are, then we earnestly hope that you can make it.

It’s all kicking off on Saturday, October 2nd at Los Angeles Convention Center—the biggest hydroponics and indoor gardening show in the world. Can you believe that? If you can’t, don’t worry—I barely can myself!

No wonder I can feel that same strange combination of nervousness and excitement returning to my stomach. But it’s the excitement that dominates. We’re bringing the entire industry together for our inaugural show in the US.

So if you’re a grower or somebody who works in a grow store who thinks they’ve seen it all before, please think again. We’ve come this far, join us for this very, very special event.

You’ve got da’ love!

Everest

An Associated Press exposé reveals how Monsanto’s onerous contracts allowed them to manipulate, then dominate, the seed industry using unprecedented legal restrictions. One contract provision, for example, “prevented bidding wars” and “likely helped Monsanto buy 24 independent seed companies throughout the Farm Belt over the last few years: that corn seed agreement says that if a smaller company changes ownership, its inventory with Monsanto’s traits ’shall be destroyed immediately.’”
“We now believe that Monsanto has control over as much as 90 percent of (seed genetics). This level of control is almost unbelievable,’ said Neil Harl, agricultural economist at Iowa State University who has studied the seed industry for decades.”

Troy Roush is one of hundreds of farmers accused by Monsanto of illegally saving their seeds. The company requires farmers to sign a contract that they will not save and replant GM seeds from their harvest. That way Monsanto can sell its seeds— at a premium— each season.

Although Roush maintains his innocence, he was forced to settle with Monsanto after two and a half years of court battles. He says his “family was just destroyed [from] the stress involved.” Many farmers are afraid, according to Roush, because Monsanto has “created a little industry that serves no other purpose than to wreck farmers’ lives.” Monsanto has collected an estimated $200 million from farmers thus far.

Roush says, “They are in the process of owning food, all food.” Paraguayan farmer Jorge Galeano says, “Its objective is to control all of the world’s food production.” Renowned Indian physicist and community organizer Vandana Shiva says, “If they control seed, they control food; they know it, it’s strategic. It’s more powerful than bombs; it’s more powerful than guns. This is the best way to control the populations of the world.”

Our food security lies in diversity— both biodiversity, and diversity of owners and interests. Any single company that consolidates ownership of seeds, and therefore power over the food supply, is a dangerous threat. Growing your own has never been so important.

WORDS: Jeffrey M. Smith

Come to Grow 2010 in Los Angeles on October 2nd to hear Jeffrey M. Smith, bestselling author of the #1 book on genetically modified organisms and bestsellers Seeds of Deception, and Genetic Roulette, present shocking evidence on the dangers of genetically modified food, and what we can do about it.

www.grow2010.com
www.ResponsibleTechnology.org
www.NonGMOShoppingGuide.com

What’s an indoor grower’s worst nightmare? pH problems? Don’t think so. Clogged drippers? No, think again. Spider mites? You’re not even close! Okay, you’re probably way ahead of me by now. Every grower’s worst nightmare has to be … an electrical fire! Often these fires are caused by faulty electrics and/or overloaded sockets. Novice growers are constantly putting themselves and their loved ones at risk by not planning their grows right. And here at Urban Garden HQ, we want all of us to sleep tight and our plants to bloom copiously 365 days a year, year after year.  Surely, that’s what we all want out of life, isn’t it?

The most important thing to get your head around when setting up a new indoor garden is your power requirement. Modern indoor gardens use HID grow lights, air conditioners, heaters, extractors, oscillating fans … and those watts add up fast! So we’re going to take a look at the proper procedures for installing circuits and bringing in the necessary electrical wiring to safely supply all of your power-hungry devices. Next, we’re going to review exactly how to specify and install all of the circuits for a ten-light flowering room setup; this process will show you how to plan a similar setup for your own indoor garden, on virtually any scale.

Here’s the good news: Anyone with their fair share of common sense, the right tools, and a healthy ‘do-it-yourself spirit’ can safely install the power for almost any indoor garden setup. However take heed: you need to pay careful attention to what you are doing and work from a predetermined plan—There’s no room for guesswork when planning your indoor garden’s electrical system.

And, once you have planned your installation, it’s a must to run your plan by a licensed electrician before doing anything. This is the smartest thing you can do.

Residential Electricity

Okay let’s take it from the top. Before bringing power to the garden, here’s a quick review of the residential electrical system. In Canada and the United States, a residential electrical service drop consists of three wires that enter a home from an overhead pole, or sometimes from an underground service feed. Of these three wires, two are separate 120-volt lines of different phase, and one is a neutral line. This type of service is called a “single phase” electric power system and it can supply households with 120- and 240-volt power circuits.

In the picture below, you can see the main point of entry for the three service wires coming in from above and entering a conduit on their way to the main service panel of a residence.

From their main point of entry into the residence, the three service wires proceed to the main panel where they connect to the meter, and to bus bars where circuit breakers snap in. The circuit breakers provide branch circuit protection for the various appliances and rooms in the house. The main service panel will always have a main fuse or circuit breaker that can cut power to all of the branch circuits—Always turn this off before working on the panel or any of the circuits. Service capacity for residential panels is usually 100, 150, or 200 amps at 240 volts. Older homes may have outdated panels with lower capacities. Before setting up in an older home, it is highly recommended that you upgrade your main panel to comply with current standards. It’s the only way you can ensure your electrical system will be safe.

This picture shows a residential panel with the door open to expose the branch circuit breakers. Note the conduit at the top left where the three service wires (two hot and a neutral) enter the panel. In the middle left is the meter, which measures overall electrical consumption. Each of the circuit breakers provides power to a certain area of the house or to a specific appliance. The blue sticker next to the breaker in the middle indicates the main shutoff.

At the main panel, a fourth wire—the ground—is introduced into the household system. The ground provides a path for current to escape in case of a circuit fault. On a proper main panel installation, there will be a copper grounding rod driven at least ten feet into the earth, with a wire that runs up to a grounding bus bar in the panel. NOTE: Some older electrical systems have what is referred to as a ‘mechanical ground,’ where the ground is made from the neutral bus bar at the main panel. The ‘mechanical ground’ method is not appropriate, and if you have an older panel with a mechanical grounding system, it is recommended that you upgrade your panel, or install a grounding rod and locate all of your ground wires on an isolated grounding bus bar.

The picture below shows a grounding rod driven in to the earth, with a wire that runs up to the main panel. This is the proper method of grounding your electrical system. Fault currents are carried directly to the earth.

From the main panel, you can create 120-volt and 240-volt power circuits for your garden by installing the appropriate circuit breaker(s) and wiring. Before selecting and installing the new circuits, first determine how much capacity you will need.  In order to do this, make a detailed list of the equipment you will be using and how much power each device consumes, in volts, amps and watts. NOTE: Devices running on 240-volt power are more efficient than those running on 120-volt power. So when selecting components, always buy everything you can in a 240-volt configuration.

Volt (V): A measure of potential electrical energy, akin to electrical “pressure.”

Amp (A): A measurement of the flow of current.

Watt (W): The overall measure of energy being consumed, in relation to time. A ‘kilowatt hour’ is the usage of 1,000 watts for one hour. This is the measurement by which customers are charged by their utility company.

Formulas to remember:

• Watts = volts x amps
• Amps = watts / volts
• Volts = watts / amps

With any two variables, you can determine the third.

CATALOG YOUR EQUIPMENT

Now to assemble the equipment list: For this task, it’s a good idea to use a spreadsheet because it can perform all the calculations for you, and you can easily analyze electrical needs for different configurations by changing variables like the number of lights, fans, etc. This setup will be running a ten-light flowering room, a six-light vegetative room, fluorescents to light some racks for cuttings, a 5-ton AC system, plus accessories like pumps and fans. The table below shows the breakdown of the equipment and electrical needs. Look at the devices to see the voltage, amperage, and/or wattage they use. Remember, you can determine the third variable if you know any two. Fill in the table completely and calculate your amperage requirements.

Since many of the devices for the model setup will be running continuously, de-rate the total amperage of the devices to determine the appropriate size breaker. To de-rate the amperage for devices running more than three hours straight, divide the total amperage that the devices are consuming by .80.

(Download this MS Excel template at www.powerboxinc.com/hydroplanner)

DETERMINE YOUR POWER NEEDS

Now that you’ve determined how many amps the devices use, and de-rated that number, assess the size of the circuits needed. Keep in mind, each major appliance group will require its own circuit. In this case, you will need to install the following circuits:

1. The first circuit you need to install will supply 240 volts and 60 amps to a lighting controller that will supply power for ten 1,000 Watt high-pressure sodium lamps and ballasts.

2. The second circuit will be 240 volts and 20 amps, to supply power for a lighting controller that will power six 400W metal halide lamps.

3. The third circuit will be 240 volts and 40 amps, to supply the power for a 5-ton air conditioning system.

4. & 5. The last two circuits will each be 120-volt, 15-amp circuits and will supply power for all of the accessories and controllers.

SURVEY YOUR PANEL

Naturally, make sure that your panel has the capacity to handle your electrical needs. This setup would require at least a 150-amp panel to run the proposed loads and have room to install three 2-pole circuit breakers and two single-pole circuit breakers. A panel survey is the first thing you should do before evaluating the potential of any grow location.

SELECTING THE PROPER WIRE GAUGE

Now that you know the size of the circuits and breakers to be used, you need to determine the size (gauge) of the wires needed. Before doing this, let’s quickly understand how many wires are needed for each circuit.

• A 120V circuit consists of a single 120V line (from either phase), a neutral line, and a ground, for a total of three wires.
• A 240V circuit consists of two 120V lines (of different phase), a neutral line, and often a ground, for a total of four wires. Some legacy 240V circuits and 240V circuits 20A or less may use a 3-wire configuration, which consists of two 120V lines (of different phase), and a neutral line (not a ground), for a total of three wires.

It is vital to select the proper wire gauge to support and deliver the power to your garden. Using the correct size wire for the amperage requirements of the circuit allows power to flow to your devices with minimal resistance, and prevents the wire from overheating and potentially starting a fire. Always remember that the smaller the wire’s gauge, the larger the wire’s diameter.

Two factors determine the wire gauge required for installation. First is the length of the wires, and second is the amount of current the wires need to carry.  The table below provides a guideline for the wire gauge required for the circuits. For medium length wire runs of 75 feet and under, use 400 circular mils per amp. For longer wire runs of 75 to 150 feet, calculate requirements by using 700 circular mils per amp.

In our example, the distance is less than 75 feet, so our calculations are based on 400 circular mils per amp.

Circuit 1: 65 feet of wire for a 60-amp, 240-volt circuit. 60 amps x 400 circular mils per amp = 24,000 circular mils. Referencing the chart reveals you’ll need to use 6-gauge wire, which has 26,244 circular mils. A total of 4 conductors are needed: 2 hot, a ground, and a neutral.

Circuit 2: 65 feet of wire for a 20-amp, 240-volt circuit. 20 amps x 400 circular mils per amp = 8,000 circular mils. Referencing the chart reveals you’ll need to use at least 10-gauge wire, which has 10,384 circular mils.  A total of 4 conductors are needed: 2 hot, a ground, and a neutral.

Circuit 3: 50 feet of wire for a 40-amp, 240-volt circuit. 40 amps x 400 circular mils per amp = 16,000 circular mils. The chart shows that 8-gauge wire would be sufficient, but it’s close. When in doubt, always go with a lower gauge. In this case, use 6-gauge wire, which has 26,244 circular mils.  A total of 4 conductors are needed: 2 hot, a ground, and a neutral.

Circuits 4 & 5: 65 feet of wire for each of two 15-amp, 120-volt circuits. 15 amps x 400 circular mils per amp = 6,000 circular mils. Referencing the chart, you should use 10-gauge wire for this circuit. A total of 3 conductors are needed for each circuit: 1 hot, a ground, and a neutral.

BRINGING CIRCUITS TO THE GARDEN

So far you’ve determined: how many circuits are needed, the necessary capacity of those circuits, and the wire gauge needed to support the current the equipment will be consuming. The next step is getting the wires from the main panel to the place where they need to be—the garden area. This is another step that requires very careful planning. In an installation such as this example, there is no other safe choice than to use Electrical Metallic Conduit (EMT).

EMT is metal tubing that comes in various diameters and it shields the wires from weather and any other outside contact. It’s easy to work with, provided you have a few of the right tools.  Don’t use something like Romex that can be cut easily or punctured in a rugged garden environment. Choosing proper tubing for your conduit is one step that helps everyone sleep soundly at night!

Next, decide where the termination for each circuit will be and then plan an accessible route for them—from your main panel, where each conduit will begin, to the location where the power is needed. You will have to make various bends in the conduit along the way; try to make as direct a route as possible so as to minimize the wire length and minimize conduit bends. Fewer bends make it easier to pull the wire through later. Connectors are available to mount conduits to the panel enclosure, to splice pieces of conduit together, and to join them to almost any type of electrical box. Mount the EMT securely using the companion clips.

The photo below shows a 1” diameter EMT conduit originating from the main panel and running along the side of a house to the grow space. A conduit like this can carry the four wires needed for the 240-volt, 60-amp circuit for the lighting controller.

This photo shows an EMT conduit using a connector to directly enter the interior of a residence via a hole drilled straight through the wall.

Now you’re getting somewhere. Once the conduit is secured firmly in place, it’s time to start pulling the wires through. Be sure to buy at least 10 feet more wire length than you need for each circuit you are pulling.

When buying wire, buy:

BLACK for 120 volt phase 1

RED for 120 volt phase 2

WHITE for Neutral

GREEN for Ground

When pulling wire, you’ll need a fish tape, which is a thin, flat steel wire ribbon on a reel, used specifically for pulling wire through conduit—be sure to get one that will accommodate more than the length you need to pull. Push the fish tape from the termination point of the conduit back through until it reaches the entrance at the panel. Make sure the main is OFF!! Carefully pull about two feet of fish tape out so that you can securely tape the wires (you’re about to pull) to the fish tape. Using black electrical tape, attach the wires in a staggered manner so that they will round bends easier when they are being pulled through the conduit. With one person feeding the wires in at the panel, and another person reeling-in the fish tape at the other end, carefully feed the wires all the way through the EMT conduit from the panel to the room.  Repeat this process for each circuit, until all of the raw wires for each circuit are in their respective conduits and sticking out at both ends.

Now, that’s easy, isn’t it? Yeah, I know, not really—it’s actually pretty rough. But don’t fret—you’re actually getting closer to the part where you hang the lights, and take some cuttings, etc.

INSTALLING THE CIRCUIT BREAKERS

Now that all of the wiring is in, it’s time to install the individual circuit breakers. If you haven’t done so already, make a trip to your local electrical supply store and get the five circuit breakers specified for the five circuits:

1. 60A Double-Pole Breaker
2. 20A Double-Pole Breaker
3. 40A Double-Pole Breaker
4. 15A Single-Pole Breaker
5. 15A Single-Pole Breaker

The cover to the main panel should already be off; if not, remove it to expose the bus bars where the breakers actually snap in. Starting with the first circuit, a 240-volt, 60-amp breaker, locate the four 6-gauge wires for the lighting controller circuit where the conduit enters the panel. Trim the wires to length and secure the white wire to the neutral bus bar in the panel. Do the same for the green ground wire—trim to length and secure to an isolated ground bar. Next, trim the red and black wires, strip the ends about 3/8”, and attach them to the terminal lugs on the 60A breaker. Tighten the screws very tightly. Route wires neatly on the side and snap the breaker into its location.

This picture shows the main panel with the protective cover removed. Circuit breakers easily snap into place once wires are attached. The neutral wire for each circuit connects to a neutral bus bar and the ground to a ground bus bar.

This photo shows a close-up of where the hot wires connect to the terminal lugs of the breakers. A double pole breaker has two hot wires (red and black). A single pole breaker has one hot wire (either a red or a black). You can spot a double pole breaker by its double thickness and the bar tying the two switches together.

Repeat the breaker installation process meticulously for each set of wires and each circuit breaker. It is critical to connect all neutral wires securely to the neutral bus bar and the ground wires to an isolated ground bar. Once all of your circuit breakers are installed and all wires are securely attached, double-check everything for accuracy. Make sure all wires are routed without being pinched and make sure breakers are firmly in place. If everything looks good, replace the security cover on the panel, but make sure to leave the main and all of the breakers in the OFF position.

TERMINATING YOUR CIRCUITS

This junction box allows connections to be made from incoming wires to devices or power outlets.

Now you need to terminate each circuit and install the devices. It’s a bit beyond the scope of this article to discuss installing all of the garden components, but we will show you how to terminate the first 240-volt, 60-amp circuit and install the lighting controller that powers all of your lights—the largest power consumers in your garden. Test with a meter to ensure there is no live current at the termination point before beginning to work on anything.

When the wires from the 60-amp circuit punch through the outside wall to the inside room as in the earlier photo, they enter a junction box like the one pictured below. Inside this box, wires are connected together and routed to their destinations through additional conduits if necessary. In this case, this junction box ties into a Powerbox™ lighting controller that powers and controls all of the ballasts and lights in the garden.

INSTALLING A LIGHTING CONTROLLER

Now there’s one last step for this circuit that is equally as important as all of the previous steps. You need to install the high-voltage lighting controller to handle the switching of all of the ballasts and lights. The high-voltage lighting controller takes more punishment than any electrical component in your garden, so it’s essential to pick the best quality. Cheap wall timers and inadequate controllers are often the cause of overload that can lead to fire. The on and off cycles of heavy amperage loads cause extreme arcing, and a lighting controller needs to handle these extreme conditions without being prone to failure.

Firmly secure the lighting controller to the wall in a location near your junction box where the circuit enters the room. Route the cable from the 240-volt lighting controller (e.g. Powerbox™) into the junction box and secure with an EMT-type terminator to the junction box. Splice each of the four wires from the lighting controller main cable to the matching wires from the incoming circuit (black to black, red to red, white to white, green to green). Use insulated lug-type connectors, which are available at electrical supply stores. Once the connections have been made, close-up the junction box. You are now ready to test this circuit. Safety first: 1. Make sure the Powerbox (lighting controller) breaker is OFF. 2. Go to the main panel and turn ON the 60-amp breaker for this circuit. If the breaker stays on, all is good so far. Go back to the lighting controller and turn the breaker ON. You should now have live power at the lighting controller!

Although each device will be a little different, repeat the circuit termination process for each of the remaining four circuits. None of them will be any more difficult than the one you’ve just done. For the 120-volt circuits, try to locate your outlet boxes close to where they will be used. This means extra conduit, but it’s worth it to avoid using extension cords, which are a garden hazard.

This photo shows a 60-amp circuit terminating with a Powerbox™ lighting controller, which in turn runs ten 1,000-watt Galaxy digital ballasts. This particular setup also uses 10 Flipbox® switches to double the production of the garden by running two parallel rooms with 10 lamps each, all off of one 60-amp circuit. All equipment is securely mounted to the wall with steel struts.

So much done in so little time. If you are building or upgrading an indoor garden that you hope will provide years of bountiful productivity, you need to build a solid infrastructure. This requires an investment of time and money, but the rewards are huge. I can’t tell you how many setups I’ve seen that have wires duct-taped together and that use pie tins as lamp reflectors. Are you kidding me? How can situations like that not eventually lead to a fire?  And to make matters worse, these are the most under-productive gardens around. Whether your indoor garden is your passion or your business, make the right moves and don’t become another statistic at your local fire department.

Now you’re at the point where it’s time to hang the lights. I don’t think you need me anymore. I’m outta here!  Peace.

P.S. Safety First! Consult with a qualified electrician before doing anything!

WORDS: Jeff Fenley, Powerbox Inc.

Rather than being charged with the task of building a modern, industrial world from scratch—just as in Sid Meier’s upcoming new release “Civilization V”—the challenge posed by Depopulus couldn’t be more diametrically different. Instead players start with a technically advanced but overpopulated world and have to get rid of 90% of its population—all without raising any alarm bells.

You start with the golden key for world domination—a complete monopoly over its monetary systems. With just a few mouse clicks you can saddle governments with debt and they, in turn, are forced to use their people as collateral to pay the eternal interest.

“You’ve gotta’ keep governments in your pocket and the people afraid of each other!” said Lloyd, an enthusiastic gamer from Brookyln, “Thank goodness we have TV!”

“It’s kinda’ like a huge human livestock management program,” grinned Charlie, another game tester, “Herding humans, keeping them both sedated yet productive, even the artificially very intelligent ones, is not easy. But the real challenge is the cull.”

And it’s the “cull” that’s causing the stink—the game’s insidious goal to reduce the world’s 6.9 billion population by 90% before all the oil, fresh water and food runs out. Techniques at your disposal include: world wars, contaminating water and food supplies, weather modification, manmade earthquakes, manmade diseases, forced vaccinations and even spraying the air with hazardous chemicals. Parents, teachers and religious groups are up in arms, calling for the game to be banned on moral grounds. But when challenged over the suitability of mass homicide for video game entertainment, game designer Nevis-Gonzalez is quick to point out that none of it is real, whereas graphically violent war games have been in the popular domain for decades. “There’s no blood, guts or gore in Depopulus.” he explained, “You’re too far removed for all that!”

Be warned – if the population gets wise to your plans, lack of tax revenue may be just the beginning of your problems. In Depopulus, puppet governments can fall in minutes, not days. And hyperinflation can wipe out whole economies in seconds. But you know the game is really over when the bots start cooperating with each other and begin growing their own food.

All traces of the game “Depopulus” have been removed from the Internet. This webpage will self destruct in 10…9…8…

Ready for a revolution?

This article is the first in a two part series about aquaponics that will first describe aquaponic gardening, then focus on the practical details around the components of a thriving aquaponics system; from the fish, plants and bacteria to the grow beds, fish tanks and plumbing options.  Hopefully by the end of the next article I will have convinced some of you that aquaponics should be at least a part of your growing repertoire, and given you the tools you need to get started.

It seems appropriate that we start our journey together by answering the question: What is aquaponics?  At its most basic level aquaponics is the marriage of aquaculture (raising fish) and hydroponics (growing plants in water and without soil) together in one integrated system. The fish waste provides organic food for the growing plants and the plants naturally filter the water in which the fish live.  The third and fourth critical, yet invisible actors in the play are the beneficial bacteria and composting red worms.  Think of them as the Conversion Team.  The beneficial bacteria exist on every moist surface of your aquaponic system. They convert the ammonia from the fish waste that is toxic to the fish and useless to the plants, first into nitrites and then into nitrates.  The nitrates are relatively harmless to the fish and most importantly, they are the foundation of great plant food.  At the same time, the worms convert the solid waste and decaying plant matter in your aquaponic system into vermicompost which supplies the remaining micronutrients.

Here is the rest of the story

• Aquaponic Gardening enables home fish farming. You can now feel good about eating fish again.
• Aquaponic Gardening uses 90% less water than soil-based gardening.
• Aquaponic Gardening is four to six times as productive on a square foot basis as soil-based gardening.  This is because with aquaponic gardening, you can pack plants about twice as densely as you can in soil and the plants grow two to three times as fast as they do in soil.
• Aquaponic Gardening is free from weeds, watering and fertilizing concerns, and because it is done at waist height there is no back strain.
• Aquaponic Gardening is necessarily organic. Natural fish waste provides all the food the plants need. Pesticides would be harmful to the fish so they are never used. Hormones, antibiotics, and other fish additives would be harmful to the plants so they also are never used. And the result is every bit as flavorful as soil-based organic produce, with the added benefit of fresh fish for a safe, healthy source of protein.
• And if you are already a hydroponic gardener considering switching over to Aquaponic Gardening you can enjoy the following advantages:
  • Aquaponics has been shown to be more productive than hydroponics after the aquaponic bio-filter is fully established. (study by Dr. Nick Savidov, of the Crop Diversification Center South, Alberta Agriculture Food and Rural Development at Brooks, Alberta, Canada report in the “Aquaponics Journal,” 2nd Quarter, 2005)
  • EC (electrical conductivity) tracking is replaced by tracking of Ammonia, Nitrite and Nitrate.  Once your system is fully cycled you will only need to measure these about once a month or so vs. the much more frequent tracking of EC.
  • pH is much more stable, again once your system is fully cycled.
  • Fish feed is significantly less expensive than hydroponic nutrients.
  • You never dump out your nutrient solution!  Rather than having problems with chemical imbalance that you regularly experience in hydroponics, in an aquaponic system you are achieving a natural nitrogen balance that is the hallmark of a balanced eco-system.  I view the water in my system as a critical component that I have nurtured into the near perfect balance at which it stays for as long as I choose to run  my system (in my case, already years).
  • Best of all, you can say goodbye to pythium forever.  It is non-existent in aquaponics.

Types of Systems

AquaBundance by The Aquaponic Source

Deep Water Culture (DWC) is where most of the university research on aquaponics has focused.  This is especially true at the University of the Virgin Islands where Dr. James Rackocy has spent the past 30 years perfecting this growing technique.  In DWC, the fish are held in tanks separate from the plants.  The solid fish waste is removed from the water using a settling tank and clarifying filters before it is sent onto the plant raceways.  This prevents the plant roots from becoming coated with solid matter and suffocating.  The fish water then circulates through a raceway that is covered with floating rafts.  These rafts have holes in them to accept planted net pots whose roots dangle directly into the water.  Newly planted rafts are dropped into the beginning of the raceway.  The rafts progress along the raceway with each newly planted raft pushing the older rafts to the end of the raceway where they are pulled from the water and harvested.  DWC is an excellent aquaponic growing technique for commercial growers because it is relatively easy to plant, tend, and harvest a large number of fast growing plants such as lettuces and some herbs.  DWC also provides very stable water temperatures and pH levels because of the high volume of water required.  The downsides of DWC are that in filtering the solids you lose many of the micro-organisms required to grow healthy, larger, fruiting plants.  Also, while it has been done, it is difficult to grow larger plants to full size because of the challenges of getting enough oxygen to the larger root zone of a plant that lives its entire life in the water.

AquaBundance by The Aquaponic Source

Most media-based grow systems use a timer to turn the pump in the fish tank on and off.  A typical timer cycle is 15 minutes on followed by 30 – 45 minutes off and then the cycle repeats.  When the pump starts, water from the fish tank is pumped into the grow bed.  The grow bed fills with water up to about 10” or so.  This provides plenty of water and nutrients for the plants.  Hydroton or other media above this height are in the “dry zone” and stay dry all of the time.  When the water reaches about 10”, any additional water immediately returns to the fish tank through an “overflow” mechanism.  The returning water strikes the water surface in the fish tank; thereby creating turbulence which helps aerate the fish tank water.  When the timer turns off, the pump stops and the rest of the water in the grow bed returns to the fish tank.  This period of inactivity gives the roots a chance to dry out and “breath” the air – something they greatly appreciate.  Then, when the timer triggers the pump again the cycle repeats.

Fish

Every aquaponic system starts with the fish and there are a wide variety from which to choose. The most important thing to keep in mind is to use freshwater fish. But which fresh water fish to raise?  To figure this out, start by deciding whether you want to grow fish for food or for show.  If you are interested in growing edible fish, tilapia are most commonly used in aquaponics because they are a tasty, fast-growing fish that have low oxygen requirements and aren’t very fussy about their aquatic environment.   Tilapia are generally purchased at fingerling size (3 – 4”) and take 9 – 12 months to reach “plate” size (approximately 12” and 1.5 pounds).  Many other edible fish can be raised as well, including trout, catfish, and perch.  Don’t be afraid to try other species.  Just be sure that  when you create your fish environment, you plan for optimal water temperature, sociability, and diet for which ever species you have chosen. Trout, for example, require a tank environment similar to the mountain streams from which they come.  This means water temperatures at 55° or below and plenty of oxygen.  They are also carnivorous, so it is impractical to grow other species with them or represent a variety of ages and sizes in the same tank.
After you have chosen your species, you will have to decide how many fish to put into your tank. The safest stocking density is one pound of mature fish for every 5 gallons (19 liters) of water.  This works out to roughly one fish for every 3 gallons (11 liters) of water, depending on the size of the fish.  Another good general rule of thumb is to have a minimum of 50 gallons of water to grow an edible fish to plate size.  If you are inclined towards keeping your fish as pets instead of food, you can go with a much smaller aquarium and use any freshwater fish you would adopt from a pet store.

Plants

People are growing almost every kind of plant in aquaponic systems.  The main exception is acid-loving plants, like blueberry bushes. The converted fish waste creates a near perfect, complete plant food that can be augmented if necessary.  Occasionally iron, calcium and/or potassium nutrient deficiencies show up but all can be corrected using small quantities of minerals that are safe for the fish (I have only supplemented once in almost 2 years of growing).
In an aquaponics grow bed, there is very little competition for food, water, and oxygen.  This means you can space plants much closer than you can in soil – up to twice as dense.  The only real consideration regarding plant density is competition for light in the canopy of the mature plants.  Make sure to plan for the ultimate size of each plant vs. its neighbors so that each plant will get the sunlight or grow-light exposure that it needs.   If you make a mistake, however, don’t lose sleep over it.  The root ball of an aquaponically grown plant tends to stay fairly compact, making most plants generally easy to move around even when they are mature.

When deciding what to plant, avoid cultivating too many of one type and age of plant in a single grow bed. A monoculture in aquaponics often leads to a simultaneous harvest, and harvesting many plants at once can put a system off balance.  Remember, your plants are filtering the water for your fish so be sure to keep a steady supply of seedlings on hand to replace harvested crops.

Consider companion planting to fight pests, as well.  For example, planting marigolds in your system can help ward away some insects.  If you do get a harmful insect infestation on your plants we recommend using insecticidal soap and/or neem oil as a safe, organic way to solve the problem quickly.  Do so carefully, however, because the fish aren’t crazy about having even organic pest controls in their water.  Avoid “bug bombs”, even if they are approved for organic use.

Beneficial Bacteria (Microbes) and Worms

Bacteria are the engine of an aquaponic system. Without nitrifying bacteria converting the ammonia to nitrates, the fish would quickly die from ammonia toxicity and the plants would starve for lack of nutrition.  Nitrosomonas bacteria convert the poisonous ammonia into nitrites and then nitrospira bacteria convert the nitrites into nitrates.  The process where the bacteria are naturally established is called “cycling”, and takes about a month. We will go into the mechanics of how to initiate and speed up cycling in a later article, but know that after becoming established, bacteria will colonize on all surfaces of the system that stay in contact with the fish water.

Be careful not to use chlorinated tap water when filling a tank, as chlorine will kill the nitrifying bacteria in the system. To remove chlorine from tap water, use a dechlorinating filter, or top off your tanks on a frequent basis with only a very small amount of water (less than 5% of the water volume), or establish a separate de-gassing tank.  Chlorine will “off-gas” (i.e. the chlorine leaves the water as a gas) on its own within a couple days, and more quickly if you add aeration.  Chloramine is also harmful to nitrifying bacteria and the fish and, if present, must be filtered from the water.  Contact your municipal water supply to find out if there is chloramine in your tap water.

Like a fine wine, the bacteria in an aquaponics system will get better over time—becoming more stable and effective.  It takes about a month to become established in your system but after 6 months it will outperform any traditional soil based or hydroponic system.  Be sure to treat the bacteria in your system like the precious friends that they are by never letting your grow bed dry out, never exposing the bacteria to freezing temperatures for an extended period of time, and never allow the bacteria to come into contact with chlorine or chloramine.

If bacteria are the engine of an aquaponic system, worms are its secret weapon.  Now the secret is out!  Add composting red worms to your media-based aquaponics system after a few months to break down the solid fish waste into vermicompost.  Vermicompost is extremely beneficial for the plants.

Next Issue

In the next issue of Urban Garden magazine we will go through what you need to know to build a media based aquaponics system, including grow bed considerations, fish tank considerations, plumbing how-to (timer, siphon, and flush valve), and considerations around the media.  The third article will conclude the series with instructions on starting up and operating your system – cycling and starting up the bio-filter, adding the fish and plants, operating your system and maintaining it, and hints on spotting problems.  My goal is that by the time we are done taking this journey together you will have the knowledge you need to start on an aquaponic adventure of your own.

Stop reading this. Please. Make sure you’ve completely dialed in your grow first. It’s far more important! Perfect your daytime and nighttime temps, keep a tight grip on your relative humidity, maintain optimum light levels, exact your feeding regimen, the works – all of it, get it right first.

The techniques described in this article are NOT for beginners and some of this stuff is nothing short of contentious. (Hmmm, a sure way to peak your interest though, eh?) We’re going to discuss methods of taking your plants to their outer limits and making them go a little bit crazy in the process. So, if you’re coming with us on this journey, buckle up, put on your questioning hat, and hold on to it tightly! Here we go …

Personally, I don’t care for stress, especially that special kind imposed by magazine publication deadlines. But I have to admit, one positive effect these deadlines have is to make me work harder!
So what about plants? We all know that unfavorable growing conditions (e.g. high temperatures and low relative humidity) can stress plants out big time. And if these conditions are severe enough you’re the quality and quantity of your yields will suffer. Invariably badly stressed plants will yield less than plants that have been pampered in every way.
Similar to most things in life, plants stress is not as black and white as you may think. In biology, stress can actually strengthen an organism. Immunity is obtained only from being subjected to an infection which involves suffering followed by growth, resistance and strength. In the human body a muscle cannot grow without being subjected to stress; a broken bone, when it sets properly, binds stronger than it was before and for that reason is very unlikely to break a second time at the same juncture. I’m sure many of you will have heard the phrase “What doesn’t kill you makes you stronger” or “Treat ‘em mean, keep ‘em keen”?  Well to a certain degree there is some truth in these sayings.

So with all this in mind is it at all possible that some forms of mild plant stress can actually improve results? The idea that stress can actually be a positive thing may seem alien to some of you. Why would you purposely want to stress plants? Surely stress should be avoided at all costs, right? Well the answer is “yes” and “no.” Here we explore the realms of stress; types that should be avoided and others which may well help you push your plants from being lazy and complacent into restless and eager producers!

Defining Plant Stress

There are many factors that will cause plants to become stressed, most of which can be grouped into two general categories -
Physical / Mechanical Stress:
Manipulation – Bending or training stems, physically damaging the plant.
Pruning – Removing leaves, stems, flowers or fruits.
Denial – not allowing a certain physical growth factor; e.g. blocking light, preventing pollination

Environmental / Abiotic Stress:
Water – drought, over-watering.
Temperature and Humidity – Cold (chilling and freezing), heat, wet or dry.
Mineral deficiency or toxicity – incorrect fertilization or salinity.
Pests and disease.

Danger Stresses

Temperature
High heat in your indoor garden can create a myriad of problems, the most common of which are tall leggy plants with large intermodal spacing, small fruits and loose flowers, high water usage, lower nutrient tolerance, and if temperatures remain high for long periods the stomata will close, plant growth will slow right down and may even cause severe wilting. Low temperatures are less problematic for indoor growers but can occur and cause slow growth and poor nutrient uptake.

Humidity
Low humidity during hot weather is a common problem that should be monitored and avoided as it will cause elevated transpiration and high water usage, increased susceptibility to over fertilization, leaf roll, stomata closure, and stunting. Periods of very low humidity can also cause wilting. On the flip side, high humidity will invite fungal infection to take hold and will slow the uptake and transport of water and nutrients.

Watering/Irrigation
Consistently irrigating the root zone beyond the plant’s usage capability causes a depletion in oxygen. These anaerobic conditions create a poor environment for root growth, cause poor water and nutrient uptake and favors the development of root diseases. A persistent lack of moisture around the rhizosphere can cause wilting, weakened leaf tissue, permanent root damage and nutrient precipitation in the growing media.

Light intensity
Having the grow lights too close will cause localized high heat and low humidity, this will lead to elevated transpiration and may result in permanent leaf tissue damage. Not having enough light tends to create poor plant growth as low water and nutrient uptake occurs. It most commonly causes elongated stems and large intermodal spacing.

pH
All good growers understand the importance of their nutrient solution’s pH and keep it within the range of 5.5-6.5, thus allowing nutrients to be available for uptake. If the pH swings out of this range for prolonged periods then nutrients that your plants need will be unavailable or  ‘locked out’ which will eventually lead to mineral deficiencies

Nutrient Strength
High nutrient levels can cause permanent damage to your plants.  Symptoms include tough leathery foliage, very dark green growth, leaf curl, poor water uptake and leaf tissue necrosis (death). Low nutrient strength is not so damaging but can also create unwanted characteristics such as soft weak stems and leaf tissue, mineral deficiencies, leggy growth and poor fruit and flower development.

Pests and Disease
Aside from pests physically eating the leaves and causing direct tissue damage, they can also spread disease from plant to plant or make a plant more susceptible to diseases and infections. Plants can usually recover from pest attack if the problem is dealt with quickly but diseases are a little more tricky. Above ground, fungal diseases like powdery mildew or botrytis can be controlled once they have infected the plant but root pathogens, viruses and other forms of invasive diseases are difficult, if not impossible to shift once they have taken hold.

Heard all this before? Okay, well now it’s time to introduce some more concepts that may not be so familiar…

How Can We Use Stress To Our Advantage?

It’s good practice to do all you can for your plants during propagation and their early growth stages because keeping plants healthy during this time is crucial when creating healthy vigorous plants. As plants mature and start producing fruits or flowers, small amounts of stress applied in the right way can actually help to improve the plant’s favorable characteristic. This may be an enhanced flavor, early ripening, elevated resistance to disease or enhanced chemical/medicinal characteristics.
Positive stress techniques are often used in commercial horticulture as a tool for influencing or ‘steering’ plants into a growth habit which the grower desires. Steering plants with mild stresses can influence the plant into shifting its efforts from vegetative growth into fruit or flower production.

Vegetative Steering

Sometimes you want your plants to grow, sometimes you want them to bloom. Most growers are familiar with using their light cycles to steer photoperiod sensitive plants. But this is just the tip of the iceberg. For most cultivated fast growing plants, “mild conditions” play a large role in steering the plant towards a vegetative growth habit. Here are some examples:

Lower nutrient strengths
The idea here is that by using a low nutrient strength you makes it easy for plant to take up water and nutrients through the roots. Obviously, you need to supply enough nutrients so as not to cause any deficiencies or unwanted growth characteristics (stretching/ long internodal distance), so supplying your plants with just above the minimum to reach these requirements will make it ‘easy’ for the plant, less stressful and therefore help keep the plant vegetative.

Wetter Root Zones
By regularly replenishing the growing media or root zone with water and nutrients without allowing dry periods to occur, the grower allows the plant easy access to water and nutrients, helping to steer the plant in a vegetative direction. It’s not good practice to purposefully over water the root zone in an attempt to steer vegetatively – all this will do it drive out vital oxygen and impede root function. The aim is to understand your plants’ (and growing media’s) water requirements and irrigate just before the growing media starts to dry. To implement this technique, drip irrigation systems offer most control. The irrigation strategy employed should be short irrigations with a high frequency. These irrigations should supply a little more than the amount the plants are using, with only a small amount of runoff occurring. By allowing water and nutrients to be constantly available to the plant it minimizes stress and promotes a vegetative growth habit.

Warmer Root Zones
Heating the nutrient solution will make it easy for the roots to function and take up water and nutrients easily. Aiming for 70°F (21°C) will help to make it easy for the plant and steer towards vegetative growth.

Low “Dif” – Small Difference in Day and Night Temperatures
The difference between the maximum daytime temperature and minimum nighttime temperature is often referred to as the ‘dif’, and contributes significantly towards your plants’ state of growth. By keeping the dif as small as possible the grower stimulates vegetative growth and keeps the plants short and compact. This is a really crucial technique for all indoor growers to get their heads around as shorter plants tend to yield far more under grow lights. Ideally, to keep plants vegetative and squat you should aim for a dif of no greater than 7°F (4°C). Time to buy that block heater!

Mild Environmental Conditions
To steer plants vegetatively, it’s important that the environment is as stress free as possible; therefore efficient temperature and humidity control are vital. Stress free growing conditions will be created if plants are able to transpire comfortably and create assimilates (sugars) via photosynthesis effectively. This will be achieved if the air temperature and humidity is within the plant’s comfort zone, generally 60-70% relative humidity (RH) with the air temperature between 68-77°F (20-25°C) – these conditions should make it comfortable for the plant to function vegetatively .

Generative Steering

Encouraging plants to flower quickly is a key skill for every indoor grower to acquire. The last thing any of us want are tall, stretching, leggy plants that force us to raise up our grow lights.  To get the most out of grow lights indoor gardeners aim for shorter, compact plants with wide canopies – the best way to harness as much of that precious incident light energy from grow lights as possible. To influence the plant’s speedy shift from a vegetative growth into flower or fruit production (generative growth), most indoor growers cultivating photosensitive plants will alter the light cycle and change out the nutrient solution from a ‘grow’ formula to ‘bloom’, and maybe use a few blooming additives through the cycle. This may meet the plant’s basic requirements  to start producing fruit or flowers, but selectively using mild stresses can not only trigger your plants into generative growth more quickly and efficiently, but it can also help focus your plants, throughout the flowering stage, to drive their efforts into producing copious amounts of flowers and fruits. These generative steering tools include:

Higher Nutrient Strengths
By raising the strength of the nutrient solution you are effectively increasing the concentration of mineral salts around the roots. This situation makes it more difficult for the plant to uptake water. When carefully managed, raising the nutrient strength to just below your plant’s upper tolerance will create a mild stress around the roots and steer the plant towards generative growth. Before undertaking this measure it is important you know your plant’s nutrient tolerance, some species and even different varieties within species will be able to tolerate more nutrient than others. Most importantly, you must have good environmental control to implement this stress technique. If you have problems with low relative humidity (below 50%) or do not have good temperature control, I strongly advise against using high nutrient strength as a steering tool as you will most likely cause problems with over feeding. Only with optimum environmental control can you accomplish generative steering with elevated nutrient strength.

Drier Root Zones
Allowing the growing media to dry slightly between irrigations also causes mild stress. The aim is not to completely restrict the availability of water and certainly not to allow the plant to wilt. The goal is to allow the growing media to dry to a point where the roots are ‘worried’ that water is running out, but not so much as to allow complete dehydration of the root surface. Implementation of this is fairly simple, during veg you water little and often to stimulate vegetative growth so during flower you water larger volumes less frequently. You don’t have to alter the total volume of water given during a day, just the timing of the irrigations. Once aging this technique is most controllable with drip irrigation systems.

Irrigation Start and Stop Times

As well as the frequency of the irrigations, the start and stop time can also be used as a steering tool. During the night your plants still use small amounts of water, this creates a drying back of the growing media during the night cycle. The more the growing media dries overnight, the more of a generative action it has. If the growing media is not drying much during the night it may be because you are irrigating too close to the lights turning off, which is more suited to vegetative growth. Your chosen time to stop and start irrigations will be determined by the growing environment but generally, starting one hour after the lights come on and one hour before they go out will be a good base to start from. If you hand water your plants in veg, say 35 fluid ounces (just over a liter) each day and you get a small amount of runoff, you could change to watering 70 fluid ounces every two days to make your plants more generative.
Word of warning; if the growing media dries too much and does not receive enough nutrient solution to re-saturate it, the nutrient strength in the growing media will start to rise. This will add to steer the plant generatively, but may lead to over fertilization. Always ensure that during the peak irrigations you supply enough solution to re-saturate the growing media and achieve 10-20% runoff.

Colder Root Zones
If you have some degree of control over the temperature of the nutrient solution you can stimulate generative growth by slightly cooling the solution. A drop from 70°F (21°C) down to 65°F (18°C) will make it slightly more difficult for the roots to function, but they will still be more than able to take up water and nutrients effectively. This mild root zone stress will not harm growth, it will just nag at the plant and push it in a generative direction.

Larger Difference in Day and Night Temperatures
Increasing the dif is known to have a positive generative action for most cultivated plants. However, it is not always good for plants that grow large fruits or flowers for the temperature to drop much below 65°F (18°C) as the transportation of assimilates made during the day can be affected by cold nights. If you have moderate day temperatures (75°F/24°C) and cannot achieve your desired dif, you may find it beneficial to raise the day temperatures to enough to keep the plants growing healthily (80°F/26.5°C) in order to enable you to increase the daily dif. To steer plants generatively try to aim for a dif of around 15°F (8°C).
Rapid late evening temperature drops have been used by greenhouse tomato growers for many years as a way of forcing assimilates towards the fruits. A quick fall in air temperature causes the plant to also cool down, but the leaves cool much faster than the fruit. This difference in internal temperature causes a draw of photosynthetic assimilates from the large leaves, which have been working hard to make sugars throughout the day, to be translocated to the fruits to advance growth. These quick pre-night temperature drops are not so difficult to achieve in an indoor garden because when the grow lights switch off, temperature often drops quickly. As long as the temperature falls enough to quickly cool the leaves, and is them maintained at a reduced level, the fruits or flowers can often stay warmer than the leaves for more than an hour. This maybe a mild stress technique you are already employing without realizing it!

Slightly Harsh Environmental Conditions (warmer temperature, lower RH)
One of the most severe stresses you can inflict on a plant is environmental stress. High temperatures coupled with low RH will make it near impossible for most cultivated plants to grow successfully. However, if you have optimum environmental control systems in place, a slight increase in day time temperature combined with a slight decrease in RH can have a significant impact. If, for example, during vegetative growth you are maintaining the day time temperature at 75°F (24°C) with 70% RH, a slight increase for a few hours each day to 80°F (26.5°C) while maintaining the same RH will increase plant metabolism and transpiration rates for short periods creating small periods of mild stress. During these periods the plant is still fairly comfortable and able to function properly but these slightly harsher conditions steers the plant more in the direction of generative growth.

Elevated CO2 levels
Higher CO2 levels in the growing environment increases photosynthetic rate. This in turn creates and provides more assimilates to the developing fruits and flowers. This means better fruit and flower initiation and overall more fruit or flowers on the plant which guides the plant in a generative direction. Dosing CO2 early in the light cycle will have a more generative action as this is when peak growth occurs.

Crop steering techniques are great tools to have in your arsenal when trying to get the most from your plants. When growing vine (indeterminate) tomato varieties or sweet and chili peppers you want to harvest fruits for as much time as possible, generative or vegetative steering techniques can be used to balance the plants into a state of constant production e.g. not too vegetative and not too generative.

When growing short cycle plants like bush (determinate) tomato plants or flowering annuals, the goal is to push the plant from a vegetative direction and force it into a generative state and keep it as generative as possible. This will result in one big flush or fruits or flowers to be harvested in one go. Generative steering techniques are extremely valuable when used in the later stages of a short cycle plants life to help it drive all its efforts into generative production.

Other positive stresses

So, mild stress can be used keep plants growing in your desired direction, but what other stress techniques are out there that may be able to help us achieve better results?

There are many myths that circulate in grower circles about techniques to enhance quality and quantity. One that I would like to quash before we go any further is the stress technique of inserting a nail through the base of the stem. Many times I have heard “This old grower I know says hammering a nail through the stem just before the end of the plant cycle makes the final fruits smell and taste better”. Total BS! Hammering anything into your plant is a sure fire way to majorly stress it out, potentially reduce yield considerably and result in very little change to your end produce. May this myth die a horrible death, much like the hammered plants will.

Topping
Topping is a technique that most growers are familiar with to transform a tall skinny plant into a short, wide bush. Removing the growing tip reduces ‘apical dominance’ which is where the central stem is dominant over other side branches. By removing the growing tip early the plant’s life, many side shoots grow which helps indoor growers create a more even canopy when growing under lights. Removing the growing tip causes some considerable stress to the plant but creates much more productive and controllable plants in the long run.

Thinning
Thinning or complete clearing of bottom growth is a technique often utilized when growing indoors to concentrate the plant’s efforts into producing good quality fruits and flowers that are bathed in light. Stems, leaves and flowering sites that are in complete shade will end up producing very little, so removing them may cause some initial stress in the short term but the plants will benefit from more concentrated growth in the long term. Many growers say that the thinning process, when done in the early stages of the flowering cycle helps to speed up the onset of flower. It may be that the removal of plant material stresses the plant in a generative direction. Fruit thinning is often carried out when growing cucumbers, peppers and even apples. Removal of some of the smaller fruits helps divert energy toward the larger fruits and results in better quality large fruits rather than lots of small ones.

Diverting Energy
When growing sub terrain crops like garlic and potatoes, growers want the plants to put all their efforts into producing those underground delights. To help them do this growers stress the plants by removing the flowering stems when they appear in midsummer. This stops the plants investing energy in fertilizing their flowers and producing seed, and focuses their attention into producing large tubers or bulbs. The picture below show the effect of removing the flowering stalk, aka ‘scape’, from the garlic plants compared to leaving them on. Significant increases in yield can be made using this technique.

Air Pruning
Air pruning roots is another great example of positive stress. It works by allowing the root tip to come into contact with air. During this process the root tip die dies back through dehydration. Although this process is fairly stressful to the root system, it actually enhances it. Once the tip dies it promotes secondary root branching along the length of the root. Once these secondary root tips come into contact with air, they too become air pruned which stimulates more root growth. Much like pinching out the top of the plant to create a bushier plant, allowing the root tip to dry creates a more branched root system within the growing media. Air pruning can be done successfully with rockwool blocks by placing them on a wire rack allowing air to pass underneath them, or with specialized air pruning pots such as ‘Smart Pots’ or ‘Air-Pots’.

Humidity
Plants that are grown for their aromatic qualities can sometimes benefit from brief periods of humidity stress during their final stages of development. As the leaves and flowers reach maturity, a sustained drop in RH can cause the plant to production more essential oils. Apparently this is a defense mechanism to further protect their leaves and flowers from the dry air.

Anecdotal grower reports on positive stress

The following are just “reports” from individual growers – so please take with a pinch of salt!

Give Me Thrips!
One grower we spoke to is now getting consistently better results now that he controls a small population of thrips in his indoor garden! This grower had a dialed in semi-closed garden and was used to getting the same yield time and time again. After a short two week holiday he came back to discover thrips had invaded and many leaves were damaged. He was not surprised when it came to harvest time to find the crop yield was significantly down. However, on the next grow he introduced the predatory insect amblysieus cucumeris in controlled release sachets. He found that by introducing these sachets every four weeks it kept the thrips numbers down to a minimum without having to regularly spray. To his surprise he found the next crop yield was up on his pre invasion average. The next crop he continued with the controlled release sachets to keep the thrips under control and again found his yield to be better than before. Is it possible that the very small amount of thrips feeding from his plants were mildly stressing the plant in such a way that it improved results? Difficult to believe but this grower was convinced.

Problem Plant
A grower had four different 4ft grow tents in one room. Each tent has one big plant in and is harvested every two weeks. That was the theory anyway… all was going well until one problem plant just wouldn’t grow. It was fine two weeks into vegetative growth and then just stopped and the leaves started to curl! At first he thought it was over fertilization, so he ran the nutrient strength much lower, one week passed and still nothing. He then thought it must be over watering so he left it to dry more between irrigations, another ten days passed and still nothing. He noticed some of the roots had started to look slight brown so he disinfected the nutrient solution with an ozone sterilizer. Still the plant looked alive, with green curled leaves but another week passed and it was still not growing!  All his friends told him to stop wasting his time and rip it out and start again but he wanted to fix it. Another two weeks passed with various attempts to fix the problem being unsuccessful until he decided to give the plant a full strength dose of nutrient solution with a ppm of 1200 (2.4mS). Boom! The plant sprung back into life the next day and grew like crazy! This poor stressed plant had been in veg for nearly 8 weeks, when it usually took 2. The long and the short of it is that although this plant did nothing for 6 weeks other than look half dead, it turned around to yield the most he ever got of one plant. Could this be down to its poor stressed out vegetative cycle? Maybe…

Cutting Stress
Another grower took cutting in pots of coir. Rooting times were 12-14 days – at this point he could see roots appearing at the bottom of his pots. On one occasion, four days after taking the cuttings, he was inspecting them when his phone started to ring. He picked it up and got distracted. Ten minutes into the call he remembered that he’d left the propagator lid off. He rushed back to his cuttings and found that many of the larger leaves had started to wilt. He quickly sprayed the lid and put it back on to quickly raise the humidity. The cuttings came back round but he was sure the stress would make the cuttings weak so he took some more as a backup. On the eighth day he checked his stressed cutting and was surprised to find that a few had roots at the bottom already! On the tenth day they all had roots at the bottom. On the next batch he did them as normal and was back to the 12-14 day turnaround, so on the batch after he purposefully took the propagator lid off on the fourth day and waited until most had slightly wilted. Once again the cuttings had visible roots between days eight and ten, as few days earlier than before. He now swears by this technique…

Spicy Stress
This grower loves his mouth to burn, and a few years back grew chilies using an ‘Autopot’ system where a valve tops up a small reservoir of nutrient solution in the bottom of the pot. It was mid July and the plants were in full swing and producing loads of fruits. One particular variety was quite mild and great in salads. One day the grower shuts off the supply valve in order to fill the reservoir with fresh water and nutrients, after filling he forgot to open the valve! An easy mistake to make but he didn’t notice for the whole weekend. Come Monday morning and all the plant were badly wilted but not unrecoverable. He opened the valve and let the plant recover. In the mean time he picked all the ripe chillies and they tasted the same as usual. He though the small developing chilled might abort but they all seem to continue growing. A few weeks later when he picked the ripe chillies the mild ones had developed a much more fierce heat level. It was the chilies that were developing during the drought stress, could it be that the short period of drought increased the spice level of the chilies?? The next set of fruits that came through were back to usual spice level so this grower is convinced that drought can influence spicier fruits.

Cold Roots
During winter, this grower liked to cold shock his roots! He grew in three gallon pots using an organic potting soil with organic liquid nutrients.  During the last three weeks of the flowering cycle he hand watered the plants with water at 55°F (13°C) once a week. He says that these cold irrigations shock the roots and the plant slightly, he does not result in any increase or decrease in yield but it does lead to a definite increase in essential oil production. The mild stress seems to work as a quality and flavor enhancer.

Wilt Shock
One grower finds that by introducing a few periods of drought stress in the last six weeks of his flowering cycle he improves plant vigor and produce quality. His technique is to let his coco coir dry out just to the point where he can see the first signs of the fan leaves wilting. He does this once during week 3, 5 and 7 and finds that the plants come back fighting after each short drought.

A Final Repetitious Word of Warning

There’s plenty of food for thought in this article. And perhaps that’s the best thing to do. THINK about it. Before we all get instantly carried away the notion that stress can be good please read and heed this final word of warning:
PURPOSEFULLY CAUSING PLANT STRESS IN AN ATTEMPT TO IMPROVE RESULTS WILL NOT MASK OTHER GROWING INADEQUACIES SUCH AS POOR ENVIRONMNETAL CONTROL OR NUTRITIONAL DISORDERS!
If you want to have a play with positive stress techniques you should do so in a controlled fashion where all aspects of your grow are completely dialed in. Only then will you know if what you are doing is positively or negatively affecting your plants. It is one thing to mildly stress a healthy plant, but to stress an already stressed plant could lead to disaster!
If you have any experiences involving plant stress (whether you caused them intentionally or otherwise) be sure to tell us about it by emailing:  rant@urbangardenmagazine.com

WORDS: Dr. Garibaldi

New York restaurateurs, John Mooney and Mick O’Sullivan, could easily use one of many farmers’ markets in the Manhattan area to keep their pantry stocked with fresh produce. Instead, however, the industrious pair decided to keep things even closer to home by setting up a hydroponic garden on the roof of their soon-to-open restaurant, Bell Book and Candle. John and Mick’s vision is to provide the majority of what appears on their customers’ plates directly from the rooftop, with all the freshly-picked produce lowered by a pulley system straight into their kitchen.

Chef John Mooney collects his bounty

The restaurant’s garden, on the rooftop of 141 West 10^th Street between Waverly Place and Greenwich Avenue, Manhattan, is now home to melons, mint, garbanzo, tomatoes, lettuce, and much more.  Their produce is grown in sixty vertical tower hydroponic systems, designed and engineered by Future Growing LLC., of Orlando, Florida. These incredibly productive, self-contained growing units allow Mooney and O’Sullivan to grow all the produce they need for their 94-seat restaurant in a relatively tiny space. The plants and white roof lining also help with keeping the building cooler in the summer.

“We went through several years of marketing and trials,” explained Tim Blank, founder of Future Growing LLC., “to develop the Tower Garden system. We never went mainstream with it until now. In the last five years we’ve made over a hundred tweaks to the system to get to the unit we have today. We found that generally people were confused by hydroponics, especially by nutrients. There are so many different types for different stages of growth and bloom. We thought there’s got to be a way to make hydroponics more accessible and relatively easy to do at home. Now we’ve simplified things enough so that two chefs, without any hydroponic experience, can manage their own roof-top farm of well over 1,000 plants.”

Rooftop solar panels help to power the irrigation system.

Amazingly it took just four days to transform the rooftop from plain black asphalt to a fully functioning rooftop hydroponic oasis! Plant starts were initially brought in from a nursery in Philadelphia but now the chefs take care of that too.
“It’s vital that the system was simple enough for anybody to use,” Tim explained. “John and Mick, like all business owners, need to stick to a strict budget. They can’t afford to hire in a full-time gardener to take care of their plants for them.” Now, just six weeks after installation, the only challenge is keeping up with the speed of growth!
“We’ve shaved 25% off the normal time needed to grow lettuce,” chef John Mooney told us. “Now we can go from seed to harvest in just four weeks! It’s incredible!”

The Tower Garden works by stacking growing units on top of a 25-gallon reservoir. Nutrient solution is pumped to the individual plant sites where the plants thrive in an oxygen-rich, soilless environment. The irrigation system is set on a timer watering the towers for three minutes out of every twelve. The Tower Garden is made from white, food-grade plastic, enhanced with UV protection so that it holds up in the unforgiving outdoor environment.

Now that’s what I call an Urban Garden! We look forward to the day when all rooftops will look like this!

Despite the sometime extreme New York weather, John and Mick are confident that they can grow on their rooftop for ten months out of twelve. Even when temperatures occasionally drop to below freezing a nutrient heater can be installed in each reservoir and irrigations are set to constant, rather than intermittent, so the roots are bathed in 65°F water. This creates a microclimate around the plants so that they can survive the odd cold snap with ease.

Mooney believes that his rooftop garden not only drastically slashes his shopping bill, but also serves as a model for others who will need to start growing food closer to home.

Plant sex in the city! Several varieties of bees have already found the rooftop garden and regularly swarm around the heirloom vegetables, doing what they do best!

“I believe in ingredients. I’ve always believed in responsible sourcing. And now I can produce what I need right here in abundance.” The chef-gardeners don’t use any pesticides. Instead, a vast population of beneficial insects protects their crops from bugs. Unbelievably, these beneficial insects found the garden—all on their own—high up in the middle of Manhattan. The rooftop is also frequented by a vast array of different bee species, all helping to keep their heirloom vegetables, including okra and red tomatillo, pollinated and productive.

“I was stunned.  There are several varieties of bees swarming the plants. From bees you could hardly see to gigantic bumblebees. Here we are in the center of New York! I have to hand pollinate my squash in Orlando! I almost dropped to my knees in awe! Ladybugs everywhere. Lacewing eggs everywhere! Predator wasps everywhere! In six weeks we’ve created an entire ecosystem!”

Inspired? We thought you would be! Bell Book and Candle is due to open to its first customers this fall.

What’s Growing?

Bell Book and Candle’s garden boasts over 70 varieties of herbs, vegetables and fruits for its lucky diners including:

Bell Book and Candle: www.bbandcnyc.com

Tel: 212 414-2355

And if you are interested in finding out more about the Tower Garden hydroponic system visit www.mytowergarden.com or come along to GROW 2010 in Los Angeles for Grower Day on October 2^nd.

Borlaug grew up in a remote corner of rural Iowa – a place with twelve- grade one-room schools from which most youngsters dropped out by the eighth grade, a place with one car, no telephones, no electricity, but the Iowa Corn Song ,3 proudly sung like the Star-Spangled Banner at the start of every school day:

There was no future, other than growing corn, but “Norm Boy’s” grandfather had another vision, and inculcated the boy with a determination to obtain a higher education. He arrived at the University of Minnesota at age 20, “as a student athlete [whose] ability to do university work was questioned” 4 but left years later clutching a Ph.D in plant pathology,.

Assigned during World War II to Dupont, where he helped to develop DDT as part of the war effort, Borlaug was offered the sky, but given the choice between Dupont and sub-subsistence science for sub-subsistence Mexican farmers, he chose the. latter, working. with the Rockefeller Foundation, in a project to stave off a looming food crisis in overpopulated Mexico.5

THE AGRICULTURAL END OF FOOD PRODUCTION USES STAGGERING AMOUNTS OF WATER. AS AN ILLUSTRATION, HERE’S A RECIPE FOR A QUARTER-POUND CHEESEBURGER

The project goal was to breed strains of wheat that could withstand adverse climates, survive wheat’s fungal diseases, and produce prodigiously on dwarf plants, then convince tradition-bound farmers to adopt forthwith the new hybrids and the technology that accompanied them.. It was a race against time, and an extraordinarily demanding task in the pre-DNA era. Borlaug set up field operations in two locations with disparate climates and growing seasons so he could have plants accustomed to multiple climates, and could grow two generations of seedlings each year.

Borlaug shortly achieved his goal, and Mexico’s food crisis was over in a decade. On to Asia, where the same thing was happening: overpopulation, courtesy of modern medicine.. India was home to some of the poorest people in the world. Famine was widely forecast for the mid-seventies. It was the era of Ehrlich’s Population Bomb. Stanford professor Ehrlich was an icon for the rising environmental movement, but overnight, stubborn farm boy Borlaug appeared to prove him wrong. In a few short years, the Green Revolution turned a land of undernourished millions into the second largest wheat producer in the world. Borlaug became the hero of millions of peasants, and also of those who spoke for unlimited growth, and in the next twenty years The Population Bomb disappeared from the environmentalist lexicon, leaving the population boom unquestioned.

The Green Revolution, which was to go on producing wonder strains for other crops and other countries, had three central parts. The other two were irrigation and chemical fertilizer. These changed agriculture fundamentally, from a primarily solar-energy craft dependent upon local weather and soil conditions, to a fossil-fuel technology designed to force the land to produce mightily regardless of its natural limitations. Borlaug, summarizing in his Nobel lecture, warned that the new hybrids had not resulted in major yield improvements without both irrigation and “a strong responsiveness and high efficiency in the use of heavy doses of fertilizers.”6 Plentiful water, plentiful chemical fertilizer – that’s the secret to how in the last half century India – and California – turned arid lands almost instantly into wildly productive garden baskets. It may not be a sustainable solution, but at the time, the world needed a quick fix.

In his Nobel lecture, Borlaug talked proudly about how the new practices had given near-starving subsistence farmers surpluses they could sell, the money to buy oil-driven water pumps and tractors, and the influence to insist upon doors opening to the broader world. If you’ll permit me a broad brush, the Green Revolution had doubled and tripled grain production for multi-millions who had been on the brink of starvation, but turned locally self-sustaining agriculture into hydroponics. And it turned subsistence farmers, dependent on the whims of the soil, sun and rain, into small-time contractors dependent on the whims of the discount rate, the commodities markets and the petrochemical industry.

It weakened their umbilical cord to Mother Earth, and eased a process in which millions would find themselves drawn to seek their fortunes in the cities, providing cheap labor to run the Indochinese economic machine. But those were events far in the future when Borlaug performed his magic, and it’s hard to quibble when several hundred million people are about to die of starvation..

The agricultural end of food production uses staggering amounts of water. As an illustration, here’s the author’s recipe for a quarter-pound cheeseburger:

Ingredient /Water used in production

Lettuce (1/4 cup)…………………………0.8 gal

Bun (2 bread slices equiv) …………………….. 22.0 gal

Tomato (1 oz paste equiv) ……………………. 6.1 gal

Cheese (1 oz.)……………………………………… 58.3 gal

Ground beef (4 oz) ………………………………..641.2 gal

TOTAL………………………………… 728.4 gal

8-oz. Glass of milk……………………… 50.0 gal 7

The reason water consumption for meat and dairy products is so much higher than for vegetables and grain, is that, very approximately, it takes two pounds of grain to produce a pound of chicken, five pounds to produce a pound of pork, and ten pounds to produce a pound of beef.

The Green Revolution doubled the world’s irrigated acreage from 346 million acres to 690 million acres, and increased by a factor of nearly five its consumption of chemical fertilizer .8 Where does all the irrigation water come from? Wells, largely; as the World Bank has pointed out, groundwater comprises 97% of the world’s accessible freshwater reserves.9

Wells are a classic case of Garrett Hardin’s “tragedy of the commons” 10 – if the aquifer is shared by multiple individuals or multiple villages and there are no rules on how much anyone can use, then the users are individually, although not collectively, better off if they use as much as they want until the wells all run dry. So unless everyone follows the Golden Rule or there is an elaborate legal “groundwater management plan,” controlling how much everyone gets, the wells DO run dry. The first thing you need to begin fair and sustainable allocation of groundwater supplies is records of pumping from wells. They don’t exist. And farmers everywhere, from the one-acre plots of North China to the 1000-acre ranches of California, rebel against interference with their freedom. Even if there were the will and the way to adopt rational groundwater management programs around the world, the task would take many decades to accomplish – unless another farm-boy-savior-scientist comes down from the sky, to whom the farmers and bureaucrats can relate.

So where does that leave us? The United States is in a relatively good position because only one fifth of its grain production comes from irrigated land, but the figure is three fifths in India and four fifths in China.11 The world-wide picture is bleak:

* The annual overdraft from the U.S. Ogallala Aquifer, producing cattle and grain in quantity, is said to be about equal to total yearly flow of the Colorado River.12 It was declared by the USDA over a decade ago to be “near depletion,” with Texas having already lost 1.4 million acres of irrigated land and the irrigated land supported by the aquifer expected to be reduced 50% by2030, an acreage accounting for roughly 10% of US grain production.

* In China, the world’s greatest grain producer,13 pumping from a fossil aquifer in the North China Plain is relied upon to produce half the nation’s wheat and a third of its corn, approximately 40 million tons per year or 10% of the nation’s grain production; 14.

* Northern India is also overdrawing its groundwater supplies to maintain grain production. Although the overdraft is apparently much less severe than in China or the United States, nonetheless, if the current level of unsustainable groundwater overdraft continues, government experts have concluded that “India could face severe water shortages.”15

* Lester Brown, founder of the Worldwatch Institute, reports that fifteen nations containing half the world’s population, rely on groundwater overdraft for irrigation.16

These practices cannot go on for long, and in this writer’s opinion, water development and conservation are unlikely to come to the rescue. large surface reservoirs and desalinization are unlikely to save the day, because these projects do not ordinarily pay for themselves and for the foreseeable future governments are unlikely to be in a position to subsidize multi-billion-dollar investments in concrete and steel to feed the poor. As for water use efficiency, it might theoretically permit savings of anywhere from 10-40%, but implementation and enforcement have all the hurdles of groundwater management plans, plus the additional hurdle that tens of millions of farmers were taught decades ago that plentiful water was essential to high yields. Changes may occur, but they will most likely be incremental and slow. So dropping grain production appears inevitable in the US and China, and likely in much of the rest of the world, in the absence of major increases in acreage and/or yield per acre.

As for increased acreage, there is general agreement that the acreages have been at best essentially “flat” for decades17 and in any event it is hard to envision major investments being made in land development to feed the undernourished and virtually destitute bottom seventh of our population when the same land could be used, if at all, to produce beef or biofuels for the top seventh.

Yields? They are still increasing at approximately 1% per year, not enough to keep up with population increase; in fact, world per capita grain production peaked in 1986.18 Steady 1% per year yield increases cannot, of course, solve the problem of exhaustion of fossil aquifers, likely to occur close to the same time as exhaustion of the oil supply. There are disputes as to whether or how long genetic tinkering can continue to improve yields. Eventually we have to hit the maximum efficiency at which photosynthesis can occur, but there are radically different educated views as to how close we are.19

In Lester Brown’s view, “Unless population growth can be slowed quickly, there may not be a humane solution to the emerging world water shortage.”20 The statistics appear to show that he should have said population growth must be “reversed quickly,” rather than merely “slowed quickly.”

So when the aquifers run dry, a return to the days when agriculture was limited to natural precipitation, is inevitable. This means, on top of the present inability of yield increases to keep up with population increases, a relatively abrupt loss of at least 10% of production.

What about the fertilizer? That comes from mining operations, too. That is literally true of phosphorus, although it wasn’t before we came along. There are more phosphorus-rich bones walking the face of the earth than ever before in geological history; humanity is hoofing it around with 5 billion kg or 11 billion pounds of phosphorus ,21 which comes from mines,22 – NONE of it recycled. This has happened only since half of us moved to the cities, taking our personal wastes with us; petrochemical fertilizers replaced natural ones; and community sewers were invented. Mama Nature can’t afford this kind of progress for long.

In fact, the world phosphorus reserves are expected to be depleted within 25 to 70 years, depending upon where you are. Humanity will apparently go extinct for lack of phosphorus within a century unless we resume recycling,.23 This writer is unaware of any government plans anywhere, to do so.

And phosphorus isn’t the perceived serious problem. Nitrogen is. We have a reasonable amount of nitrogen in the air for the present, but the nitrogen has to be processed into ammonium nitrate or something comparable with a high energy input, and the starting material is natural gas, 5 % of which globally is used for production of nitrogen fertilizers.24 There are presently no alternatives. Natural gas accounts for 90% of the cost of nitrogen fertilizer, so the cost of the latter is pretty much proportional to the cost of the former.25 When the petroleum supply starts to go, fertilizer prices will spiral upward.

Of course nitrogen fertilizer can also be produced by nitrogen-fixing legumes, but that necessitates alternating between nitrogen-fixers and market crops. In his Nobel lecture Borlaug spoke of a dream of nitrogen-fixing grains being introduced in 1990 that would free peasant farmers from the need to purchase chemical fertilizers, but then, he said, he would wake up, disillusioned. It was only a dream. 35 years and 3 billion more people later, he would have to tell the New York Times, “This is a basic problem, to feed 6.6 billion people. Without chemical fertilizer, forget it. The game is over.”26

So at present, grain yield is not keeping up with the population, and things will get worse as fertilizer and water become expensive and scarce. Will a large part of the population die when they are curtailed? Not necessarily, because of how we allocate the use of the grain we produce.

To see the whole picture, we need to understand a little about the grain market, which is the dominant food market.. There are at this time three competing demands for the commodity: food (i.e. direct consumption by people), fodder, and fuel. Before fuel became part of the mix, the division between food and fodder was 60:40, with the “fodder” component capable if used as food, of providing the caloric needs of 3.5 billion people.27 But we are squandering the 40% “cushion.”

The mix in 2008 was said by Worldwatch Institute to be 47% food, 35% fodder, 18% fuel. The 18% figure may not be a 2010 reality, but no one claims less than 9%, and use of grain for bioalcohol is projected to double in the next decade.28 The 18% that we burn or apparently will burn is more than sufficient to fill the stomachs of the record 1 billion people who are undernourished today. Does it give you a warm and fuzzy feeling that we burn the grain that is sufficient to eliminate world hunger? Me neither. And If we engaged in a modest conservation program in our gasoline use and gave the saved grain to the hungry, no one would have to go hungry, at least for the moment The feed use is increasingly for beef, and the fuel use is primarily bioethanol – an attempt to use the “cushion” in world grain production to let the middle class, particularly in the

US and China, indulge in quarter-pounders and gas guzzlers for a few more years, while the poor’s burgeoning undernourished try to maintain themselves on an ever-slimmer portion of the grain production.

Feed and fuel compete with food not only for consumers, but for land. The EU has adopted a policy requiring 17% of its farmland to be devoted to biofuels in place of food.29 Land from Brazilian deforestation (which of course many of us would rather see not at all) could produce grain for food, could support range cattle, or could produce sugar cane (or grain) for ethanol. Not surprisingly, biofuel and beef are Brazil’s primary products from destruction of the rainforest.30 Food comes out as a poor third in competition with feed and fuel both for grain and for land. No wonder there were riots over bread in 2008.

“THE MIX IN 2008 WAS 47% FOOD, 35% FODDER, 18% FUEL. THE 18% THAT WE BURN IS MORE THAN SUFFICIENT TO FILL THE STOMACHS OF THE RECORD 1 BILLION PEOPLE WHO ARE UNDERNOURISHED TODAY. DOES IT GIVE YOU A WARM AND FUZZY FEELING THAT WE BURN THE GRAIN THAT IS SUFFICIENT TO ELIMINATE WORLD HUNGER?”

And we have hardly looked at the inevitable consequences of an agriculture dependent for more than half its productivity on fossil fuels, outside the control of one-acre farmers in the Third World or even of thousand-acre farmers in the US. Two of the simpler ties between fossil fuels and food are the costs of fertilizer and water for a typical Third World one-acre farm. With most of the cost of fertilizer(although varying widely year-to-year and place-to-place, $100/acre is a reasonable figure) coming from the cost of natural gas, its cost is going to go up rapidly as oil runs out and (if it happens at all) as the world starts to do something about global warming. And the cost of gasoline at $3/gallon for pumping the water from an -all-too-typical 500-foot-deep well sufficient to irrigate an acre for a year is about $200.31 So rising fossil fuel costs are likely on the near term to drive up fertilizer and water coss by hundreds of dollars per acre The Ogallala-Aquifer farmer may be able to “pass the cost along to the consumer”(Brace yourselves, Americans!), but the farmer in India or China or Bangladesh has mostly to pass the cost on to herself. Where will it come from? Less fertilizer, less water, less food, with one billion people hungry already. These are of course just illustrative costs, but he writer suspects they are more accurate than the assumptions made by the U.N. Food and Agricultural Organization in its food supply projections for the next decade, that the international community will invest $200 billion per year for technological improvements in agriculture, that oil production will meet demand and that its costs will hardly budge.32 So even if the world can produce enough food, most folks may soon be unable to pay for enough.

The story of how we got here is complex – a confluence of population boom, oil boom and bust, the tragedy of the commons, misallocation of resources between rich and poor, the almost-deliberate blindness of America to the consequences of biofuel production -. the list goes on. There is an ongoing academic argument about whether the plight of the poor is one of inequitable distribution “or” population, but it is quite clear at this point that the answer is “Both.” There is also a sociological factor – the separation of people from the land, which has allowed us to “commoditize” land, to block the recycling of phosphorus and nitrogen, to separate sustenance from daily life, to warehouse in China’s cities the millions who had recently been attached for millenia to the cycles of sun and rain and soil. Out of sight, out of mind. We will not treat the earth sustainably when we do not see it and feel it in our daily lives and know directly that what surrounds us is what keeps us and our descendants alive and healthy.

There are too many of us to go “back to the land,” but we must preserve the connection. In coming decades necessity will dictate that everyone produce their own food wherever and however they can, but more important, we must reconnect ourselves to the earth we have abused. You who put aside a little corner of your urban homestead where things green can flourish are preserving the connection as best you can, and must teach others to do likewise. You are preserving an essential thread to our past, which will, if we are lucky, allow us to have a future.

But it’s a slim thread.

It didn’t need to be this way. Norman Borlaug, far from viewing himself as the man who proved the doomsayers wrong, knew what was coming if we didn’t take care. In his Nobel lecture he described the Green Revolution as giving the world a “breathing space” until the year 2000, but then referred to an “impending doom” imposed upon us by the “Population Monster ,” and told his audience that”the frightening power of human reproduction must also be curbed; otherwise the success of the green revolution will be ephemeral only.”

Dr. Borlaug said in his lecture that whether and how we deal with the population problem is a”test of the validity of “sapiens” as a species epithet.” We have so far failed the test and squandered the thirty years he gave us. But the substantial fraction of the grain crop not used directly as food can, if we act quickly, allow us without famine to put ourselves on a sustainable population track, one recognizing that we don’t presently feed ourselves and that on the present track, things will get much worse. And of course no technical fixes can give the bottom seventh of the world population the wherewithal to pay for what they eat, so the looming food crisis will not just be fixed with a theoretical food supply for which they cannot pay. These things must happen. Is that likely? Probably not, given past history. But it is necessary.

Once again we 6.9 billion people are on our own, without leaders or guidance. But we know what we must do, as individuals and nations: we must avoid gasohol and beef, because we cannot take food from the mouths of the hungry; we must manage and conserve our diminishing water supplies, we must work to eliminate abject poverty so that people can pay for what they eat and we must begin to decrease our numbers by limiting ourselves to one child per family.33 There is no evidence that we can avoid famine otherwise. The Green Revolution was a one shot deal, because we cannot again double irrigated acreage or multipy use of chemical fertilizers by five; and because the Green Revolution was a program of the oil age, which is fast departing. Modest crop-yield increases may keep up with population growth for a while (although they haven’t for 25 years), but all indications are that the prices of what food there is will rapidly climb above the budgets of billions of us.

“Norm Boy,” the Iowa farm kid, died last year. He was 95.

………………………………….

The writer is a California-licensed attorney currently residing in Massachusetts. He has had professional experience trying without success to implement groundwater management in California’s vast agricultural San Joaquin Valley. Research and writing were supported by Urban Garden Magazine, which reserves copyright and all other republishing rights except the right to online submissions by the author. He wishes to thank Patricia Lemon and David Steele for invaluable editorial assistance.

1. This article will be published by Urban Garden Magazine in mid-August.
2. Bruce Alberts, President, NationalAcademy of Sciences
3. For the full lyrics, see http://www.netstate.com/states/symb/song/ia_corn_song.htmor http://iowareunionclub.com/iowacornsong.aspx
4. Mark Yudof, President, University of Minnesota.
5. Biographical information from Vietmeyer, Borlaug, Volume 1 (2004), unless otherwise indicated..
6. Dr. Borlaug’s Nobel lecture: http://nobelprize.org/nobel_prizes/peace/laureates/1970/borlaug-lecture.html
7. See Dr. Thomas Stein, sakia.org, 2007, http://www.sakia.org/cms/fileadmin/content/irrig/general/stein_2007_water_use_charts-units_converted.pdf for a general compilation of different foods and their water needs for production, together with a link for explanations as to how these were determined.
8. See chart, Global Education Project, Food and Soil, http://www.theglobaleducationproject.org:80/earth/food-and-soil.php. A hectare, a 100-meter square, is 2.2 acres. Spend an hour studying these charts, and you will know more than the average Ph.D. about modern agriculture.
9. World Bank, Groundwater, http://web.worldbank.org/WBSITE/EXTERNAL/TOPICS/EXTWAT/0,,contentMDK:21633297~menuPK:4620525~pagePK:148956~piPK:216618~theSitePK:4602123,00.html.
10. (Garrett Hardin, 1968 paper published in the journal SCIENCE (162:12431248). If you aren’t familiar with it, read it, and then go for a vacation and meditate on it for a week.
11. Lester Brown, Aquifer Depletion, 2006, http://www.eoearth.org/article/Aquifer_depletion
12. Patricia Muir, http://people.oregonstate.edu/~muirp/waterlim.htm
13. UN Food and Agricultural Organization (FAO), Agricultural Outlook 20102019 (2010)
14. Lin Shujuan, China’s water deficit ‘will create food shortage’, Science and Development Network, 2007, http://www.scidev.net/en/news/china-s-water-deficit-will-create-food-shortage-.html; and Lester Brown, WATER DEFICITS GROWING IN MANY COUNTRIES: Water Shortages May Cause Food Shortages, http://www.greatlakesdirectory.org:80/zarticles/080902_water_shortages.htm.
15. T. V. Padma, Thirsty Indian farming depleting water resources, Science and Development Network, http://www.scidev.net/en/news/thirsty-indian-farming-depleting-water-resources.html, quoting scientists from NASA and also citing the Indian Ministry of Water Resources..
16. http://www.eoearth.org/article/Aquifer_depletion,
17. See e.g. the graphs shown in Staniford’s article cited below.
18. Patricia Muir, http://people.oregonstate.edu/~muirp/waterlim.htm
19. Stuart Staniford, Food to 2050, The Oil Drum, http://www.theoildrum.com/node/3702, discussing both sides of the dispute. See also Grain Production, http://www.whole-systems.org/grain.html, and Science’s February, 2010 issue devoted to food security. http://www.sciencemag.org/cgi/content/full/327/5967/812
20. Lester Brown, WATER DEFICITS GROWING IN MANY COUNTRIES: Water Shortages May Cause Food Shortages, above.
21. http://www.random-science-tools.com/chemistry/chemical_comp_of_body.htm
22. UN Food and Agricultural Organization (FAO), Current world fertilizer trends and outlook to 2011/12, Table 4, ftp://ftp.fao.org/agl/agll/docs/cwfto11.pdf
23. For a recent and very readable discussion of the phosphorus situation, see D.A. Vaccari, Phosphorus: A Looming Crisis, Scientific American June 2009, www.ScientifiAmerican.com.
24. Wikipedia, Fertilizers, http://en.wikipedia.org/wiki/Fertilizer.
25. GAO, Domestic Nitrogen Fertilizer Production Depends on Natural Gas Availability and Prices, 2003, http://www.gao.gov/new.items/d031148.pdf.
26. K. Bradsher and A. Martin, The Food Chain: Shortages Threaten Farmers’ Key Tool: Fertilizer, New York Times, http://bigteaparty.com/fertilizer-soaring-foodprices-key-to-health-bad-for-environment/
27. United Nations Environment Program (UNEP), Food from Animal Feed, World Food Supply, http://www.grida.no/publications/rr/food-crisis/page/3565.aspx). R. Segelkin, US could feed 800 million people with grain that livestock eat, Cornell ecologist advises animal scientists, Cornell University Science News, 1997, http://www.news.cornell.edu/releases/aug97/livestock.hrs.html.
28. Worldwatch Institute, Vital Signs, Grain Harvest Sets Record, But Supplies Still Tight, 2009, http://www.worldwatch.org/vs2009.. The UN Food and Agricultural Organization says the figure is only 9% for biofuels at this time, but also says that the amount of grain being turned to alcohol will double in the next decade. OECD-FAO, Agricultural Outlook 2010-2019. So if 18% isn’t correct today, then it is likely to be correct in a decade…
29. X. Navarro, The European Commission says no to reviewing biofuel percentage goal, http://green.autoblog.com/2008/04/15/the-european-commissionsays-no-to-reviewing-biofuel-percentage/
30. OECD-FAO, Agricultural Outlook 2010-2019.
31. 1 gallon [U.S.] of automotive gasoline = 97,181,192.2530305 foot pounds. 1 acre pumping from 500 ft.: 3 acre-feet of water = 975,000 gal water x8 lbs/gal x 500 ft = 3,900,000,000 ft lbs/ 97,181,192.2530305 ft lbs/gal gasoline = 40.131 gal x $3/gal = $120, assuming a 100% efficient pump, or $200 assuming a 60% efficient pump.
32. OECD-FAO, Agricultural Outlook 2010-2019
33. There is a time lag of 30-40 years built into any population policy based upon birth control, because a rapidly-growing population over-represents the age group under reproductive age. Consequently, a “ZPG” birth rate does not result in ZPG for decades. Moreover, the water and energy problems imply that an overall population reduction is necessary.

By Nicholas C. Arguimbau
31 July, 2010
Countercurrents.org

You’ve all heard the old adage, “Your enemy’s enemy is your friend.” Well, it’s never truer than in the world of indoor gardening! Savvy growers have been using “predators” for years. A predator is just another name for a beneficial insect – an insect that feeds on the pests you hate! Usually Mother Nature keeps everything in check. Indoors, you have to take the role of Mother Nature, otherwise a rogue pest can breed uncontrollably and quickly overwhelm your garden. With this in mind, we thought we’d put together a regular feature on predator insects. After all, it’s good to know who your friends are!

Hypoaspis Miles vs. Fungus Gnats

Seeing the first signs of fungus gnats? Allow us to introduce you to a good friend of ours: Hypoaspis miles. These guys are truly fantastic predatory insects all gardeners need to know about. This tiny mite is less than 1mm in size and resides in the top few inches of the growing media preying on a variety of soil organisms, but is especially useful for the control of fungus gnat larvae (aka Sciarid fly larvae).

What are Fungus Gnats?

The most common root pests that lurk in your growing media are without doubt the larvae of fungus gnats. These pesky little insects will usually appear in your garden as harmless looking small 3-5mm black flies. True, the black files themselves won’t actually do any direct damage to your plants, it’s their habitual egg laying that’s the problem. The flies are attracted to wet growing media, particularly organic substrates like potting soils and coco coir or anything with algae growing on it. After mating the female flies can lay anywhere between 50 and 200 eggs which hatch in two to three days. Once hatched the larvae, which look like tiny maggots, develop through four life stages or ‘instars’ over a period of two to three weeks. At the end of this period they normally reach around 5mm in length and are translucent white color with a distinctive black head. You can often see their guts throughout the length of the larvae with their previously eaten food moving through.

The larvae move through the upper surface of the growing media feeding on decaying organic material, algae and fungus but more importantly they eat living plant material, mostly roots but also stem tissue. As a result of this root tissue damage they open the plant up to a variety of disease such a Pythium, Phytophthora and Fusarium. Plants under attack from fungus gnats will often slow down in growth, leaves may discolor, nutrient and water uptake will be affected and in severe cases the plant will wilt and if left untreated it may die.

After two-three weeks of feeding the larvae will enter a pupation stage for three-four days until they emerge as an adult fly. Adult fungus gnat flies can live and lay eggs for between one and three weeks. At temperatures above 77°F (25°C) the complete life cycle from egg to larvae to adult fly takes three to four weeks.

Hypoaspis miles?

Hypoaspis are predators that feed on fungus gnat larvae, springtails, thrips pupae and other small harmful soil insects. When introduced into a growing area that isn’t already plagued by fungus gnats, they have a significant impact in reducing and eventually eradicating them. They don’t work effectively when pest number are high, mainly because they can’t eat everything!

Hypoaspis miles is light brown in color with a darker V-shaped making on its back, this dark V is due to the slightly darker dorsal shield on top of a slightly lighter colored body. They mostly live in the upper surface of growing media. In compacted growing media that may be only the first half inch but in looser more open growing media that may roam down two inches below the surface or more. Hypoaspis prefer growing media high in organic matter such as peat or coco coir but they will happily establish populations in rockwool, perlite and expanded clay pebbles too.

Females lay oval eggs in the growing media at the rate of two to three per day. The eggs hatch in approximately six days (at 68°F (20°C) but this figure is dependent on temperature) into six legged white-beige larvae. After two days they enter the protonymphal stage followed by the deutonymphal stage which actively feed for around ten days before becoming adult. The total development time from egg to adult takes between 17-18 days (again at 68°F (20°C)) when they have plenty of prey to eat. Hypoaspis miles adults can live for between 4- 5 months, and usually have an even population ratio of one female to every one male.

Temperature plays a huge role in the development time for Hypoaspis, at 59°F (15°C) the development time extend to 34 days and at temperature lower than 50°F (10°C) development almost stops. The mites will recover when the temperature rises, as long temperatures no lower than 10°C are sustained for long periods. Temperature below 46°F (8°C) and above 90°F (32°C) are detrimental to their development. At 75°F (24°C), the Hypoaspis development cycle shortens to around 12 days showing just how important temperature is to their reproduction and growth.

Hypoaspis are ferocious eaters of fungus gnat larvae! Hooray! An astonishing eight first instar larvae can be consumed by adult Hypoaspis each day! Contrary to popular belief, Hypoaspis will not eat fungus gnat eat eggs or pupae. They can attack and kill up to one fourth instar larvae per day, but as fungus gnat larvae reach maturity they can get up to seven times larger than Hypoaspis adults making it possible for them to be attacked but not completely consumed. Some uncommonly large fungus gnat larvae may be attacked but not be killed by Hypoaspis due to their size. However, the most import life stage to target is the young developing fungus gnat larvae. When these are removed fewer and fewer make it to the pupae stage which mean a huge reduction in adult flies. This effectively throws a huge spanner in the cogs of the fungus gnat breeding machine, totally disrupting their life cycle, and as the Hypoaspis population grows the fungus gnats get wiped out. Read it and weep fungus gnats!

One key attribute that makes Hypoaspis such a good biological control is their ability to last for up to 70 days without food! In the absence of fungus gnat larvae Hypoaspis can sustain themselves on nematodes, soil microorganisms, algae or in some cases decomposing plant debris, but they do not feed on live plants. This handy generalist feeding approach prevents the population from crashing after eating their way through lots of fungus gnat larvae. Once up to a healthy population size they literally form an army of mites scavenging through the growing media surface constantly in search of prey. This makes Hypoaspis an excellent preventative measure as well as a key tool in the fight against existing fungus gnat populations.

Hypoasis are also know to feed on thrips pupae, which often fall from plants and into the growing media before turning into adults. Hypoaspis are not efficient as a standalone solution to thrips control, but they are effective when used in combination with Amblyseius cucumeris (above ground thrips predator) or spray programs.

Geeky Fact
While they are mostly found below ground during the day, many entomologists have observed Hypoaspis miles climbing up stems and onto foliage low down on plants during humid nights. Here they have been observed feeding on mealybugs, thrips larvae and other organisms.

When purchasing Hypoaspis miles from your grow store, garden center or specialist supplier they most often come in a carrier material of peat and vermiculite. They are bred on this carrier material in controlled laboratory conditions using the tiny storage mite (Tyrophagus putrescentiae) as a food source. This is then packaged and sold in cardboard tubes ranging in size, the most widely used are either 17 ounce (0.5 liters) tubes with 10,000 Hypoaspis or 34 ounce (1 liter) containing 25,000. For larger growers some suppliers offer larger buckets containing a gallon or more with over 100,000 predatory mites in. The peat and vermiculite mix will contain all stages of Hypoaspis including adults, eggs and immature mites.

Left to right, 17 ounce tube, open tube showing peat/vermiculite mix, one low infestation dose

Releasing the mites into your garden is easy. Simply sprinkle the mixture onto the surface of the growing media. Application rates vary depending on the level of infestation. Most biological control companies recommend using 30 mites per square foot of ground area as a preventative measure and up to 120 per square foot for treating existing infestations. If you’re growing in pots, around one level teaspoon at the base of each plant will be enough as a preventative and one heaped teaspoon for existing fungus gnat problems. A 34 ounce container of Hypoaspis miles retails for around $40.00 (USD) and can treat between 100-200 three gallon pots.

If fungus gnats are a constant problem in your indoor garden, you should introduce Hypoaspis predators one to two weeks after planting into the final pot/system. Top up two to three weeks later with a second application to help build up the Hypoaspis population.

Top Tip!
Before distributing the mites into your garden roll the tube back a forth a few times and leave it on its side for ten minutes. This will create a more uniform spread of Hypoaspis mites within the peat-vermiculite mix before dispersal. If stored upright for too long all the mites will try to make their way to the surface of the mix which will lead to the first few applications getting all the goodies.

Hypoaspis are sensitive to some chemical foliar pesticides as run-off can drip onto the surface of growing media. Pyrethrum products and more importantly their synthetic cousin’s permethrin and bifenthrin will have longer term harmful consequences on the growth of Hypoaspis populations and should be avoided. Be sure to check the compatibility of your chosen pesticide with your predators before application.

If you are struggling to control fungus gnats in your garden and you need a quick fix help the Hypoaspis predators get on top of the situation try using a bacterial larvicide containing Bacillus thuringiensis israelensis (Bti). This bacteria kills the active larvae but not Hypoaspis. Another compatible bio-control is the beneficial nematodes Steinernema feltia. These natural microscopic parasites will infect the fungus gnat larvae quickly and effectively without harming the Hypoaspis mites.

Using sticky yellow traps around the canopy and at the base of the plants is also great idea. Not only will these trap the adults and prevent them from laying eggs, but they can be used as monitoring cards to keep an eye on fungus gnat numbers. Simply look at the cards, make a note of the amount of flies trapped and replace the traps each week. A steady decline in fungus gnat numbers should be observed after releasing the predators.

In a nut shell

Hypoaspis miles eat:

1) Preferentially; fungus gnat larvae and thrips pupae

2) Secondarily; other tiny soil organisms algae and plant debris

They will:

1) Control fungus gnat population keeping the pest to a minimum and over time eradicate them

2) Aid in the control of thrips species that pupate in the growing media

Should be used:

1) When fungus gnat numbers are low

2) When growing media temperatures are above 10°C

Should not be used:

1) As a sole treatment for a fungus gnat infestation, they will not be able to cope with the amount of pests.

2) As a sole treatment for thrips.

3) In conjunction with pesticides before checking compatibility. 

Here’s our guide to setting up a basic, conventionally ventilated indoor garden on a budget. We’re going to show the different ventilation requirements for a 2 light and a 6 light grow in the same space.

Big rooms need lots of lights with a high-powered ventilation system whereas small rooms will only need a few lights with a low powered ventilation system. All sounds like simple stuff, doesn’t it? But how do you work out exactly what your room needs? Here’s what you need to consider:

Size

All of the equipment your new indoor garden will need comes down to the size of the room. So, the first thing you need to do is accurately measure it. You will need the length, width and height of the room.
The example shown has the dimensions of:
Length x Width x Height
24ft (7.2m) x 12ft (3.65m) x 8.2ft (2.5m)

Now before we get carried away filling this room with lights and fans, you have to consider the budget and ability of the grower undertaking this new project. A confident and experienced grower may well fill the whole room, but let’s not bite off more than we can chew. First, let’s create a smaller room within the larger room by sectioning off the back portion to give a working room size that is more suited to a beginner.
Length x Width x Height
12ft (3.65m) x 8ft (2.4m) x 8.2ft (2.5m)

You might well be asking, “What are the benefits of sectioning off the room? Why can’t I just hang the lights in the corner?” Well, by creating a room within a room you gain better control of the environment. With the sectioned off area you make the best use of the available light by having walls lined with reflective sheeting – this creates a bright well-lit environment for productive growth.

You can use various materials to section off the room but the better insulated, the better. A well insulated room will immediately lend itself to far easier environmental control.

If you have no interest in building your own indoor garden, or you’re not too confident with your DIY skills then don’t worry, help is at hand. You can purchase purpose-built indoor grow tents – highly recommended for all levels of grower! These come in many sizes, with one bound to suit your requirements, and it makes hanging lights, fans and filters a sinch.

Lighting

Now you know the size of the room you’re working with you can calculate how best to illuminate it. The most widely used light source for indoor gardens is high intensity discharge (HID). They are widely available, competitively priced and produce consistent results. Two types of lamps are able to run in HID systems; High Pressure Sodium (HPS) and Metal Halide (MH).
HID lighting systems are available in many different sizes, but the most commonly used for indoor growing are 1000W, 600W and 400W. Each size light is suitable for a defined amount of floor space:

1000W = 4-5ft (1.2-1.55m)
600W = 4-3.3ft (1.2-1m)
400W = 3.3-2.5ft (1-0.75m)

One thing to bear in mind is that the more powerful the light, the further away from the tops of the plants it needs to be. This means that if you have a low ceiling height, you should consider using lower wattage lights. The example room has an 8.2ft (2.5m) ceiling height so we can use the 1000W lights, as long as the plans don’t get bigger than 5ft (1.5m) which is fine for most plants. Indoor plants want to be short and wide to make the most of the light available. The distance between the light and the canopy that most growers follow are:

1000W = 39-31 inches (100cm-80cm)
600W = 31-24 inches (80-60cm)
400W = 24-16 inches (60-40cm)

Please bear in mind that the above information is for horizontally mounted lamps in normal open or closed reflectors. If you are using parabolic reflectors with vertically mounted lamps or air-cooled reflectors you can allow the light to be closer to the plants as there is less direct radiant heat.

So the floor space available in our room is 12ft (3.65m) x 8ft (2.4m). You could try and squeeze as many lights as possible into this room, but as well as being productive, you want to try and make your room easy and comfort- able to work in. To do this you will need adequate access around your plants to make maintenance and inspections easy. Approximately 2ft (0.66m) around your plants is a good working area. Elderly or disabled growers may opt for considerably more space than this. In our first example we’re using 2 x 1000W lights.

If you want to make life difficult for yourself, you could fit a maximum of 6 x 1000W lights. In order to make this room work you would need to choose a growing system or technique that allows you to move the plants to gain access around the garden. This might be achieved by growing in pots/containers or movable beds.

Ventilation

Ventilation in your indoor garden comprises of two main factors: the removal of hot waste (CO2 depleted) air and the input of fresh cooler air. Hot waste air is removed actively using an inline fan, AKA the extractor fan. Fresh cooler air can either be drawn in passively through vents or pushed in actively using another inline fan AKA the intake fan.
Now we know the size of the room, and the amount if light being used, we can now work out the ventilation requirements. In North America most inline fans are rated in Cubic Feet per Minute (CFM), whereas in Europe they are usually rated in cubic meters per hour (m3/hr).

The Extractor Fan

Firstly, we’ll work out what size extractor fan is needed. There are many ways to work out what size extractor is needed for a particular sized room, some equations are more accurate, others are overly complicated – the following method is very popular and straight forward and has served many growers well.

Required extractor fan size in CFM= Volume of active growing area (ft) x 1.25
Required extractor fan size in m3/hr= (Volume of active growing area (m) x 60) x 1.25

When we say the volume of the active growing area we mean the volume occupied by the lights and plants. To work out the volume simply multiply the length x width x height. In our example with 2 x 1000W lights this is 4ft (1.2m) x 8ft (2.4m) x 8.2ft (2.5m), which gives the volume of the active growing area of 262.4 cubic ft (7.2m3).

Once you have your volume, you need to multiply it by the amount of air changes needed per unit of time. For the majority of indoor gardens without AC or supplementary Co2, the rule of thumb is one air change per minute. For the CFM equation there is no need to multiply it as we already have the total volume in cubic ft which is needed to be changed every minute. For m3/hr equation we need to multiply the volume by 60 to step it up to the amount of air changes needed per hour.

Lastly, when using a carbon filter attached to the extractor fan we expect a drop in fan efficiency of approximately 25%. This figure is not fixed; it depends on the make and age of the filter and the length and course of ducting between the fan and filter and many more interesting factors that we won’t bore you with here. To step up this efficiency drop of 25% simply multiply by 1.25.

If we run this equation through our example indoor garden it gives us;
Required Fan size (CFM) = (Volume of Active Growing Area) x 1.25
(4 x 8 x 8.2) x 1.25 = 328 CFM

Required Fan size (m3/hr) = (Volume of Active Growing Area x 60) x 1.25
(1.2 x 2.4 x 2.5) x 60 = 432.
432 x 1.25 = 540 m3/hr

This final figure is the minimum size extractor needed. If the garden is in a very well insulted location such as a basement using this figure should be fine. If the garden is located in a very sun-exposed location such as an upstairs bedroom or attic then the extractor size may need to be increased by approximately 25%. More often than not, you will have to match your required extractor size to the nearest size avail- able. In this instance the nearest widely available inline fan size is a 6” (150mm) 390CFM (660 m3/hr) extractor.

Interestingly, if we work though the equation for the same room with 6 x 1000W lights it will give very a different answer;

Required Fan size (CFM) =  (Room volume) x 1.25
(12 x 8 x 8.2) x 1.25 = 984 CFM

Required Fan size (m3/hr) =  (Room volume x 60) x 1.25
(3.65 x 2.4 x 2.5) x 60 = 1314
1314 x 1.25 = 1643 m3/hr

In this indoor garden the nearest widely available fan size available is a 12” (315mm) 1000CFM (1700 m3/hr) extractor.

Oversized Fans

Many growers think ‘bigger is better’ when it comes to extraction but this is not always the case. By extracting air from the garden you’re removing the heat, but you’re also removing the hu- midity. This means that an oversized ex- tractor fan can often cause low relative humidity, which will create an onslaught of negative effects that will lead to poor plant growth.

‘Summer sized fans’ are also not always the answer to a warm indoor garden. There comes a point where it doesn’t matter how much air your extracting, if your incoming air is warm your room will stay warm. If you can’t keep the heat down and you’re changing the air in your garden more than three times a minute, you need to consider installing air conditioning or using air-cooled or water-cooled grow lights.

Fresh Air

As mentioned earlier, we need to get fresh air into the garden. This can be done using two methods:

1. By making passive vents (basically holes) through which fresh air can be drawn in.
2. By installing active inline fans that push fresh air into the garden.

When using passive vents you have to ensure there is adequate fresh air outside the growing area. It’s no good if you’re pulling in stale or warm air. This means you may need to have a window open so fresh air can be drawn in from outside and into the indoor garden. As a rule of thumb, the passive vents should be two to three times the size of the surface area of the extractor fan outlet. This means if the extractor has a 6” (150mm) spigot size, the garden will need 2-3 x 6” holes or rectangular vents with and equal surface area. When installing passive vents always have the extractor fan at the opposite end of the room. It’s better to have oversized passive vents than undersized. If the vents are too small, the extractor fan will struggle to pull in sufficient quantities of fresh air.

Indoor gardens with active intake fans often run more efficiently than those with passive vents. By pushing in fresh air you not putting as much strain on the extractor fan and you also get to choose where to pull the fresh air from. During the cooler winter months its best practice not to pump in very cold air, so a lot of growers pull slightly warmer air from inside their home. If it’s a room you spend time in, like your bedroom or living room, it will also have the added benefit of the air being slightly higher in Co2. During the summer months its best to pull fresh cooler air in directly from outside as air from inside you house is likely to be warmer. Whenever you pull air straight from outside it’s best to use an intake filter or ‘bug screen’ to limit the possibility of sucking in pests.
The golden rule when installing an intake fan is to make sure you’re blowing in less air than is being removed by the extractor. This creates a ‘negative pressure’ and ensures that all the air exits through the carbon filter. If you input more air than the extractor can remove the air will start to build up and cause a ‘positive pressure’ forcing untreated air out of the garden.
When selecting an intake fan it should have a maximum capacity that is 10-20% lower than the actual output of the extractor. This will maintain adequate negative pressure while not putting too much strain on the extractor and intake fans.
To work out the intake fan size we will need to take the extractor fan size and apply an estimated reduction for the carbon filter- 25%. If our target for the intake fan is 15% less air than the exhaust we need to multiply the reduced output by 0.85. Below is a work through of how to size up the intake fan for both or the example rooms.

2 light room:

Extractor size – 390 CFM (660 m3/hr)
Estimated extractor power with carbon filter – 390 x 0.75 = 292.5
Reduction to ensure negative pressure = 292.5 x 0.85 = Intake Fan Size 249 CFM (420 m3/hr)

6 light room:

Extractor size – 1000 CFM (1700 m3/hr)
Estimated extractor power with carbon filter – 1000 x 0.75 = 750
Reduction to ensure negative pressure = 750 x 0.85 = Intake Fan Size 638 CFM (1084 m3/hr)

When installing the intake fan, make sure the extractor is at the opposite end of the garden. It’s a good idea to split the intake air with a solid ‘T’ or ‘Y’ piece so that the cooler fresh air is distributed evenly. Using air socks or longer lengths of ducting with holes in is a good way of evenly distributing the incoming fresh air.
One last factor to consider is that inline fans are better at pushing than pulling air through ducting. This means than when positioning your intake fan, it’s better to place it nearer the source of fresh air and push it towards the indoor garden. To make the air reach the garden efficiently, make sure the duct runs are as smooth and straight as possible.

Air Movement

Moving the air within the garden is of utmost importance. A light breeze moving air over the plants’ leaves refreshes the CO2 depleted air, gets rid of heat and humidity and encourages transpiration. The area of an indoor garden where most unwanted heat will accumulate is between the lights and the canopy, so it’s absolutely crucial that this air is removed to avoid heat build up. To achieve good air movement between the lights and the canopy you can install fixed or oscillating air circulation fans. These can be wall mounted or floor standing and should be powerful enough to mix the air well, while not causing the plants to be blown too vigorously. You want to move the air, not your plants! If you point strong air circulators straight at your plants the air will move past the leaves so quickly that it will strip away the humidity surrounding the leaf and encourage rapid transpiration. This leads to the leaves losing water rapidly and can cause them to appear burnt at the edges crispy to touch; this is known as ‘wind burn’. If you need to enhance the air movement around your plants, it’s a good idea to point air circulators towards walls rather than directly at the plants to mix the air adequately while not causing the plants to be flapping around in turbulent wind.

Equipment location

To avoid unnecessary heat transfer, any equipment that generates heat should to be stored outside the garden. Most notably, the power packs (aka ballasts) that can get quite warm need to be situated outside the garden on a shelf or any non flammable surface. Having them outside the room also is best practice for electrical safety as they won’t be operating in a warm and humid environment and will not have risks of stray foliar sprays landing on them or accidental splashes of nutrient solution.
Nutrient solution will also benefit from staying outside the garden. Your reservoir will quickly heat up under the direct light from your grow lights so its best practice to locate your reservoir outside the garden.

Any liquid nutrients and additives should not be stored in hot or cold environments. It’s best to consult the packaging and see what the best environment is for your products but most appreciate a constant moderate temperature. This should again be outside your garden.

Summary

Following the above principles you can construct your- self a great, budget indoor garden, suited around you, while creating the ideal environment for your plants. All you need to do after this is choose a method to grow your plants whether it’s growing passively in plant pots, or using an active hydroponics system such as an Ebb and Flow, Drip, or NFT – all will flourish in your well planned indoor garden.

NEXT TIME:
We will be looking at selecting the best growing system to suit the needs of you and your garden and using fan speed and environmental controllers.