Everest shares some time-honored heuristics to help beginner growers increase the productivity of their indoor gardens.

1.) Reduce Your Concentration!

Hydroponic growers adjust the pH of their nutrient solution to around 5.8 to 6.2 – this provides the best accessibility to the widest range of nutritional elements.  pH adjuster products are sold in grow stores in concentrated liquid (sometimes powder) form.  However, some growers get lazy and add this stuff neat (undiluted) to their nutrient solution.  This causes nutritional elements to precipitate out of the solution and therefore become unavailable to your plants.  To avoid this, make up a dilute solution of your pH adjusters – 1 part pH adjuster to 100 parts water – and use this instead.  The weakened concentration of your pH up or down will enable you to safely adjust the pH of your nutrient solution without damaging your nutrients!

2.) So Near, So Far …

More light = more yield … but only to a point!  In fact, grow lights can represent a mixed blessing for the indoor gardener.  Sure, they provide the all-important light photons essential for photosynthesis – your plants ain’t growing without them!  But these same lamps also generate a lot of radiant heat!    If your plants grow too close to your lamps they will become too hot and shut down (stop photosynthesizing).  In extreme cases they will scorch and burn and the growth tips will die.  This causes untold stress to your plants and drastically reduces your yields.

On the other hand some growers are overly cautious and raise their grow lights too high, causing their plants to stretch in search of more lumens.  The ongoing aim of every indoor gardener is to get as many growth tips in the “sweet spot” as possible.  This is the area where your plants are just at a safe distance away from your bulbs and receiving maximum light intensity.

Different growers combat this problem in different ways.  All growers should try to move the air in between the tops of their plants and the lamp using an oscillating fan.  Some growers also air-cool or water-cool their grow lights while some put their lights on a mover or spinner.

As well as a light meter, use a thermometer with a remote temperature probe to measure the heat at the tops of your plants.  For many popular indoor crops, the magic number is 82°F (28°C).  What’s the temperature reading at the top of your plants?

3.) Brrrrr!  Using Cold Tap Water!

First off, tap water can contain chlorine and chloramines plus high levels of other minerals (often not in a form that is useful to your plants) and other impurities.  You should always feed your plants with the best quality water you can.  Many professional growers and keen hobbyists take control over their water quality by investing in a water softener and reverse-osmosis water purifier.  Also, you should always make sure that the temperature of your nutrient solution is around 65 – 68°F (18 – 20°C) before feeding it to your plants.  Cold water shocks your plants’ roots and warm water contains drastically lower levels of dissolved oxygen.  If your indoor garden is suffering from high temperatures, using a slightly cooler nutrient solution can help your plants get through until you manage to correct your environment.

4.) Lights++ Environment–

So, you’ve managed to dial in your indoor growing environment with two, three or four lights and you’re growing healthy, happy plants and enjoying regular crops of your favorite veggies all year round.  Great, but don’t make the mistake of thinking you can expand by simply adding more lights!   You need to also consider how this will effect your growing environment.  Firstly, more plants will mean more transpiration, and a need for more CO2.  More lights equals more heat to get rid of.  So if you are thinking of adding more grow lights, make sure you budget for increased air transfer too – you’ll definitely need it!

5.) Unruly Plants

A crucial skill that every indoor gardener needs to learn is how to shape and train their plants so that they make the most of any artificial light source.  You need to let your plants know who’s boss.  Do not grow your plants too large.  Small to medium sized specimens are the way forward for most indoor growers.  Remember, your plants receive exponentially less light the further they are from the lamp.  As most gardeners light their plants from above, a common goal for many indoor growers is for shorter, squatter plants with wide canopies.  Think of a candelabra.  Pruning out the leading growth tip will encourage many types of plants to adopt this formation.

TIP:  If you are growing plants that are sensitive to photoperiod bear in mind that they will not respond immediately when you change your light cycle to induce flowering.  Growers of many plant varieties are often stunned by the amount their plants bolt (or stretch) after changing the day length simulated by their grow lights.  Err on the side of ‘small’ when deciding when to switch your plants from vegetative to flowering mode!

6.) Grow Like A Gardener, Not a Robot

So you think you’ve got your nutrient recipe down and now it’s just a question of making it happen.  But the best growers are always in a state of flux.  They are observing their plants on a daily basis, getting in among them, looking for signs of under / over fertilizing and adjusting their nutrient regimen accordingly.

This is especially important if you are making any chance, whatsoever, to your growing environment.  Improved air exchange or CO2 levels in your indoor garden will cause your plants to grow more vigorously.  The saavy grower observes and recognizes this and increases the strength of his nutrient solution accordingly.

Conversely, if the ambient temperature inside your indoor garden rises above optimum levels (e.g. during the summer months) your plants will inevitably use more water.  You should therefore decrease the strength of your nutrient solution.

7.) Stale Food

Re-circulating your nutrient solution?  Great – you’ll save on precious water resources, not to mention expensive nutrients and additives!  But ask yourself – how often do you really drain your reservoir, then rinse, and replenish with a fresh batch?  Once every week?  Once every two weeks?  Or once every … when you can be bothered?  Younger plants will tolerate less frequent nutrient solution changes than more mature plants.  But if you’re really going to turn on the charm, the time for super frequent nutrient solution changes is during flowering and fruiting.  This is when your plants’ nutrient requirements are at their highest and will benefit most from regular nutrient solution changes.

8.) Poor Propagation

Care early on pays massive dividends later.  Be especially patient and watchful during the propagation stage.  Give your plants time to establish healthy root systems before rushing them into a hydroponics system and flowering them off.  Ensure humidity levels are kept fairly high at 60-80%, especially early on.  This reduces stress on the young plant which, in turn, allows it to focus on that all-important root system.

A plant that has been “hardened off” for five or six days under a fluorescent veg lamp, for instance, still needs to be introduced to a 1000W metal halide with care.  Raise the metal halide 3-4 foot above the plants until you see the first signs of growth.  Break those babies in slowly.  What is often diagnosed as “transplant shock” is often more due to the shock of an increase in light intensity.

9.) Lack of Oxygen

Dissolved oxygen in your nutrient solution is so important we can’t harp on about it enough.  Oxygen in your nutrients promotes root health and speeds up your plants’ metabolism meaning it can grow faster and bloom copiously!  Lack of oxygen in your nutrients, on the other hand, invites all sorts of problems, the leader of the pack being pythium which can destroy your crop in a matter of days.  You can increase levels of dissolved oxygen in your nutrient solution by bubbling air into it – the smaller the bubbles, the better!

10.) Don’t Be a Dirty Sanchez

What’s that carpet still doing in your indoor garden?  Is that decomposing plant matter in the corner over there?  Still not got rid of that bag of old root balls from last crop?  Get a grip on your garden!  Clean as you go.  Keep it as spotless as possible.  Filter all air vents.  Think of your indoor garden as a laboratory and you won’t go far wrong.  The cleaner your growing environment, the fewer viruses your plants have to fight; the more energy your plants can put into their primary mission – growing and blooming!  Cleaning sounds boring, and it is.  But how boring is 10% more yield?  Nuff said.

Greetings Urban Gardeners.

Let’s take a look at how we can get the most out of our hydroponic nutrients, otherwise known as “nutrient management.” Now, to the skilled grower, nutrient management represents an opportunity to enhance plant growth, enjoy bigger yields and achieve higher overall crop quality. However, to the novice it can represent a difficult challenge or even a complete mystery! The difference is in knowledge, understanding, environment and equipment.

Here are six questions to test your nutrient knowledge. Do you already know the answers?

Your nutrient solution should be maintained at around 68 °F (20 °C) for the best combination of oxygen content and uptake by the roots.

Q2) What is the “dissolved solids” content of the water you use to mix your nutrient and does this content vary greatly from season to season? Does your water supplier provide you with good water from one reservoir at one time of the year and bad water from a different reservoir at another?

Test your water with an EC meter before adding anything to it.

Q3) Are there any components (such as high levels of calcium or magnesium) in your water that could affect the availability of other nutrient  elements? Have you considered the presence of sodium chloride from sea-water contaminating your water supply?

Ask your water supplier to provide you with an analysis of your water. Some grow stores also offer this service.

Q4) What is the “EC” or strength of your nutrient? Do you mix special nutrient blends for different kinds of plants and for each stage of the crop’s lifecycle, or in response to different environmental conditions like high temperatures and low humidity?

If you are unable to prevent temperatures in your indoor garden from rising too high, you can decrease the stress levels for your plants by decreasing the strength of your nutrient solution.

Q5) Does the pH of your nutrient stay within a reasonable range, or does it drift up and down significantly? How quickly?

It’s quite normal for the pH of your nutrient solution to rise (say from 5.8 to 6.5) over the course of a few days – but greater changes could indicate the presence of pathogens in your nutrient solution from contamination or from sick plants that may spread disease to the rest of your crop.

Q6) Do you change your nutrient often enough to prevent imbalances from salt accumulation or deficiencies from nutrient exhaustion?

It’s really important to change your nutrient solution regularly because it helps to minimize the wastes your plants discard into the nutrient. Did you know that, as plants transpire and nutrient levels drop in your reservoir, the EC or strength of the nutrient can rise to dangerously high levels?

What’s In Your Water?

Water quality is a crucial issue for all gardeners. Success comes easier with soft water. Just add the right combinations of nutrients to the water and you’re off to a great start. However, if you have very hard water, or water contaminated with sodium, sulfide, or any number of heavy metals, your first step may be to filter your water using “reverse osmosis.”

The best way to find out what’s in your water is to obtain a seasonal water analysis through a lab. If you’re on a municipal water system, call your water district and request a copy of their most recent analysis. Keep in mind that a good analysis at one time of the year does not mean that the water quality will remain good throughout the year. During dry seasons water suppliers often switch to a different reservoir with different water quality.

Another approach – highly recommended – is to check your water regularly yourself with a dissolved solids meter, also called an electrical conductivity (EC) or parts per million (ppm) meter. These instruments are one of the most important tools for a grower to use regularly. By measuring the EC (ppm) of your source water routinely before adding nutrients, you will be able to tell if your water supply is consistent, or changing.

How Does a Conductivity Meter Work?

All dissolved solids instruments work in essentially the same way: they measure the electrical conductivity of the water. It is the dissolved salts in most water that allows it to conduct electricity. Pure water is a poor conductor since there are none of the conductive salts found in impure water. Purified water will show no, or very low, salt content (conductivity) when tested with a dissolved solids meter.

It is not uncommon to find high levels of salts in well water or municipal water supplies. Calcium and magnesium carbonates are among the most common ingredients in tap water and in well water. In fact, water “hardness” is defined as a measure of the water’s content of calcium and magnesium carbonates. In some regions sulfates can also reach high levels in water supplies.

Since calcium and magnesium are important plant nutrients, water with reasonable levels of these elements can be just fine for hydroponic cultivation. However, even a good thing can become a problem if the levels are too high. Generally, a calcium content of more than 200 PPM, or 75 PPM for magnesium, is on the verge of excessive for most hydroponic applications. An excess can cause other important elements in the nutrient solution to “lock-out” and become unavailable. For example, excess calcium can bond with phosphorus to make calcium phosphate, which is not very soluble and therefore not available to the crop. If magnesium bonds with phosphate it becomes completely insoluble and unavailable to the plant. The key to success is to start with decent water and add the right combination of nutrients.

Nutrients – A Question of Quality

What makes a quality nutrient? Here are some questions to ask. Some answers may be harder to find than others!

• How pure are the ingredients?
• How consistent is the product?
• Is it properly labeled with ingredients and NPK?
• How reputable is the manufacturer?
• What ingredients are in there and how are they combined?
• Does the product contain contaminants from poor quality control?
• If it is a liquid, did the manufacturer use R/O or purified water in the blend?
• Does the manufacturer have a quality control (QC) program like safety sealed bottles so you know it is pure and has not been tampered with?
• Are there any hidden or ‘mystery’ ingredients?

Too Hot, Too Cold

The temperature of your nutrient solution is another important factor. If your solution is too cold, seeds won’t germinate, cuttings will not root and plants will grow slowly – or stop growing and die. If it’s too hot, the same seeds won’t germinate, cuttings won’t root and plants will die from oxygen deficiency, or they will succumb to pathogens that thrive in higher temperatures, or simply bite the bullet due to temperature stress. Most plants prefer a root zone temperature range between 65 and 72 °F (18 to 22 °C), cooler for winter crops, warmer for tropical crops. When adding water to your reservoir it is a good idea to allow it to come to the same temperature as the water in the root zone before starting circulation pumps.

Remember, plant roots have evolved in a soil environment where temperature changes occur slowly, tempered by the thermal mass of the earth. Rapid temperature changes in the root zone can cause shock and invite root disease.

Water pH

A subject that is often discussed but rarely understood by many growers is nutrient pH. Plants normally grow best within a pH range from 5.5 to 6.8. Generally we worry about pH and its affect on nutrient availability. For example, if pH is too high, iron may become unavailable. Even though your nutrient solution may contain an ideal amount of iron, your plants may not be able to absorb it, resulting in an iron deficiency – the plant’s leaves will yellow and weaken.

On the other hand, hydroponic plant foods usually contain special “chelates” that are designed to assure iron availability, even at higher pH ranges. The result is that your crop will grow reasonably well even at higher pH levels. Nonetheless, high pH can damage plants in other ways. The cause of a high solution pH can be fairly complex. Most city water supplies contain calcium carbonate to raise the pH of the water and prevent pipes from corroding. As a consequence you are starting with water that has an abnormal pH: typically 7.5 to 8.0 for city water.

One method of dealing with the high pH of city water is to mix in fresh nutrient, let it stand for a while to stabilize, then test and adjust the pH. With city water supplies you will often have to add a solution of pH down (usually phosphoric acid) to lower the pH to the suitable range for most plants.

As your plants grow it is a good idea to occasionally test the pH and adjust it if needed. You can safely allow pH to drift between 5.8 and 6.8 without adjustment. In fact, constantly adjusting the pH in your system to maintain a perfect pH of 6.2 can do damage. It is common for pH to drift up for a while then down and up again. This change is an indication that your plants are absorbing nutrient properly. Adjust pH only if it wanders too far, below 5.5 or above 7.0 for example.  A pH below 5.5 or above 7.0 can spell trouble but don’t overreact. An apparently sudden and dramatic shift in pH can be the result of a malfunctioning pH meter. If in doubt, double-check with a reagent (color match) pH kit before adjusting your solution. Also remember that pH meters are temperature dependent. Read and follow all of the instructions that came with your meter or test kit. I know of at least one case where a grower lost a crop due to a defective pH meter after over-correcting nutrient pH.  Use a meter as well as a color-match test kit to double-check your pH.

Big pH swings can also indicate strong microbial life in the nutrient solution and root zone.  Microbes can change the pH to meet their needs.  The best way to manage this is to introduce beneficial microbes into your nutrient solution and the plant’s root zone. These microbes are nature’s little plant helpers.  The beneficial fungi typically help plants grow bigger, stronger and more effective root systems. The beneficial bacteria typically populate the root zone and protect the roots from bad microbes and environmental stress factors.

Time For a Change?

How often should you change your nutrient solution? That’s one of the most common questions asked and one of the most difficult to answer. Many people have tried to come up with a simple, easy-to-follow rule … once a week, every two weeks – but they’re all wrong! They’re wrong because there is no simple answer. It all depends on the plant variety, the number and size of your plants, their stage of growth, the capacity of the reservoir, the kind and quality of nutrient you use, water quality, environmental conditions such as temperature and humidity, and the type of hydroponic system used; there are so many factors that the answer is not obvious. Instead of a simple answer, what we need is a procedure that takes many of these variables into account and is responsive to changing conditions.

It sounds complicated, but it’s actually quite simple. All it takes is a little monitoring and some basic record keeping.

• Start with a fresh reservoir of nutrient and make note of the date, pH, and EC or PPM of the solution.
• As you run the system, the level will drop in the reservoir. Note the EC/PPM level then top-up the reservoir with fresh water. Test again for nutrient concentration. If the nutrient strength has dropped significantly, add a bit of nutrient to bring it back up to specs. Be sure to record how much water you added to top-up the reservoir. Repeat the procedure every time you top up the system, carefully recording the amount of water added.
• When the total amount of water added equals the capacity of your reservoir it is time to drain and replace all of the nutrient solution.

For example, imagine a hydroponic system in a cool greenhouse in the spring with 24 strawberry plants and a nutrient capacity of 20 gallons. Typically, such a system might require about five gallons of added water each week. After four weeks the plants will have transpired 20 gallons – the capacity of the reservoir. You need to completely drain and replace the nutrient every four weeks in this example.

Now imagine five tomato plants with a 20 gallon reservoir. They are fully mature, growing and producing quickly. It is hot and dry. Each plant pulls in a gallon a day so you are adding five gallons a day. After four days it is time to change the nutrient. It may be best to use a larger reservoir since the EC flux in this case will be pretty high.

Fascinated? Read on in the second installment of this feature in Issue 5 …

All sounds rather slick, right? After all, the key to huge harvests is providing a whole spectrum of optimum conditions for your plants – like a series of links in a chain. However, there’s one thing missing from this garden – an essential building block of the sort of harvests your plants want to give you. MICROBES.

Beneficial Microbes

Microbes may be small, but they’re taking off in a big way as indoor gardeners discover new ways to harness the benefits they bring. And leading the pack is John Perrino of Vermicrop Organics, California.  He’s taken some time out from his crazy microbial world to explain what microbes are, what they do, and how we urban gardeners can use them to take our gardens to the next level.

Perhaps I shouldn’t attempt to summarize everything in the first sentence, but here goes: Beneficial microbes increase the efficiency of your nutrients. Put another way, microbes allow your plants to feed more. Even the highest quality nutrients can be made more efficient through microbiology, thus increasing growth, vigor, sugars and yields. Ok, so now you know what beneficial microbes are basically about – but let’s look a bit deeper!

The basic application of beneficial microbiology in soil and hydroponic gardening is simple, really. It kind of falls under the same concept as the food chain. When a plant’s root system has a well-rounded colony of micro-organisms, it has billions of microbes doing a wide range of jobs. Some microbes consume nutrients; some microbes consume the microbes that have consumed the nutrients, thus breaking the nutrients down into a smaller form. This allows the nutrient to be absorbed by the plant more efficiently. Other microbes defend against unbeneficial microbes and keep the plant’s natural defense system at its peak performance level. Each microbe exudes different types of enzymes, proteins, acids and other essential elements. These are the elements needed to break down trace minerals, micro nutrients, and macro nutrients making them immediately available as a food source to the plant. All this really means is an explosive increase in root mass, which equals increased nutrient uptake, which equals bigger yields!!!

So if these beneficial microbes are the building block to a robust and vigorous garden, how do we get them there in the first place? Remember, these little guys are living entities. So the best way to increase the levels of microbes in your gardening system is a fresh brewed, microbial rich solution. We are talking about Actively Aerated Microbial Extracts (AAME). Now, don’t switch off on me just because I’m using acronyms already. I’m telling you that AAMEs are going to change your life!  So listen up!

So What’s Brewing?

Actively Aerated Microbial Tea

Like I said, these little guys are LIVING so they’re going to need feeding. The idea behind AAME is to take an organic material that is high in beneficial aerobic microbes and add essential food sources to raise certain levels of each type of beneficial micro-organism. To get things to multiply, dissolved air and a food source in an aqueous environment is needed. But you have to create the right conditions for these little fellas to multiply at the rates we want – using water straight from the tap is a no-no (because of chlorine levels); reverse osmosis or de-chlorinated water at the perfect temperature and the right type of food sources will allow microbes to multiply at extremely rapid rates.

Beneficial Bacteria

There are three basic groups of beneficial micro-organisms (take note there are tens of thousands of individual types of each microbe in each group). The first to be addressed is beneficial bacteria, the smallest of the three groups. They attach to your root system and feed on unavailable nutrients in and around the root web. Once a bacterium has consumed a nutrient (food), the nutrient is then immobilized (locked inside of the bacteria’s cell wall).  Here the nutrient is broken down with a mixture of different proteins and enzymes. The only way that the nutrients can be unlocked (mineralized) and up-taken by the plant is if the bacteria dies and/or is consumed by a competing micro-organism. Once this process occurs, the nutrients are released in their mineralized form and are immediately absorbed by the plant.

Fungi

Fungi, the second group of beneficial micro-organisms, are much like bacteria in the sense that they too find and immobilize unavailable nutrients. Unlike bacteria, fungi find their nutrients in a completely different way. Fungi live in and around your root web, and grow miniscule root-like strands called “hyphae”; these strands can stretch for many feet. The hyphae stretch throughout the network of the plant’s root system, usually ending on an attachment site on the root. The nutrients are then distributed in a number of different ways. Immobilized nutrients are locked up within the cell walls of the hyphae until the fungal microbe dies and/or is consumed by a competing micro-organism. The nutrients then get mineralized and passed off to the plant as an “easy to absorb” food source. Other fungi trade exudates (carbohydrates, sugars and proteins made by plants and excreted by roots) for water and nutrients; these fungal organisms are known as mycorrhizae. Mycorrhizae work in a symbiotic relationship with the plant’s roots: the fungi brings nutrients and water back to the plant’s roots in exchange for exudates collected from the roots. It’s a win-win situation. The plant then becomes somewhat dependent on the fungi and the fungi cannot live without the exudates from the plant. Through this relationship, many different nutrients are mineralized and absorbed immediately by the plant.

Protozoa

The third type of beneficial micro-organism is the protozoa. Protozoa microbes can be up to 100 times the size of bacteria and fungi. The protozoa feed on mostly bacteria and fungi (protozoas can eat up to 10,000 bacteria a day). When the protozoa consume bacteria or fungi, they mineralize any of the nutrients that were immobilized in the bacteria or fungi. This unlocks any nutrients that have been locked up in the bacteria and fungi. They are then absorbed rapidly as a food source to the plant. Protozoa are at the top of the food chain in the beneficial microbe world. This means there always needs to be a food source, otherwise protozoa will die. Luckily, as the protozoa consume the microbes they consume small bits of organic matter that are processed and exuded as food sources for bacteria and fungi. This helps keep fungal and bacterial populations sustained when conditions are right. If fungal and bacterial populations diminish, protozoa will start to eat their own and eventually die. This is why it is important to replenish microbe populations with a balanced array of beneficial micro-organisms, keeping the food chain in balance and allowing optimal performance.

The only way to get an extremely high multiplication of micro-organisms is through a fresh extracted AAME. Unfortunately, Actively Aerated Microbial Extracts are not available as an ‘off-the-shelf’ product.  To solve this issue, an on-site extraction process with a culture of biology is necessary. This process can multiply the culture of aerobic micro-organisms over 9 billion times in a 24 hour period. When an AAME is used as a foliar spray and as a root inoculant, it will raise the number of micro-organisms that work together in a symbiotic relationship with the plant to increase vigor and yield. With a high diversity of beneficial micro-organisms, plants receive a wide array of the micro-organisms that exude humic, fulvic, amino acids and proteins. These micro-organisms and their exudates aid in immobilization and mineralization of trace elements, micro and macro nutrients.  Microbes have been around for millions of years and now we have the technology to put them to use in our gardens.

Microbe Tea – Q&A

You say actively aerated microbial extracts aren’t available ‘off-the-shelf’ – so once I’ve brewed the tea do I need to use it straight away?
No – think of it like milk. It will last for 12-24 hours if stored at room temperature, or 7-10 days in the refrigerator. Use the smell test. It should have an earthy and fresh aroma if it’s good. Smells damn awful when it’s gone bad!

How much microbial extract brew is good for my plants?
For Soil: Dilute with water at a rate of 75 ml to gallon (1:50). Apply this solution directly to your soil over the root zone.
For Hydro: Use the same dilution ratio but reintroduce more microbial tea solution to your nutrient solution every 7-10 days.

Can I use boiled tap water to make the microbial tea?
No, boiling won’t cut it. You must use non-chlorinated or Reverse Osmosis filtered water. Reverse osmosis machines are more affordable than you think. Check out the Small Boy made by Hydro-Logic.

What do you think about using microbes in your garden? Do you have any tips, tricks or stories to share?