For those not familiar with Sure To Grow, allow me to enlighten. Plastic bottles are recycled and reconstituted into a growing medium that is Sure To Grow (STG). The medium feels light and fluffy. You can purchase it in any form factor that you need: sheets, blocks, loose-fill, and pre-formed cones for net pots (2″ seedling pucks up to 10″ for 2-gallon buckets).

In contrast to other mediums, raw materials are not utilized in the creation of Sure to Grow. Reduce, recycle, and reuse. Plastic bottles feed Sure To Grow. However, the tradeoff of utilizing raw, virgin ingredients which can be reused vs. waste products which would otherwise be thrown away—-I choose the medium from waste recycled products.

Why is it a great growing medium?

One of the single most important and hard-learned benefits of Sure to Grow—-plant resiliency. During the 2 years that I’ve been using Sure To Grow, I’ve had root rot occur twice. The roots started in STG popped back almost instantly. No other medium that I tried worked this well.

The reason why this occurred is that the roots were protected in the bubble that is Sure To Grow. With Hygromite (diatomaceous earth) and Hydroton (clay pebbles), root rot affected the roots up to the root ball. With Sure To Grow, root rot stopped at the medium. After trimming the foliage and affected roots, roots took 4x as long to restore with Hygromite and Hydroton than with Sure To Grow.

With STG, the entire plant didn’t have to start rerooting from scratch. The new rooting started right from the edge of the medium. BAM! Almost. . .insta-re-rooting.

Here we have a couple of pics of plants that suffered from root rot.  These shots are after 1 week and 2 weeks, respectively, from Sure to Grow in Current Culture H2O’s 4XL system.

Transplantability. Say you start your plant in dirt, or any other medium and you want to change it up. You can repot your plant into STG. You carve out a suitable cavern inside STG and insert your plant.

Transplant from dirt? Impossible, you say! Possible, says I. Sure To Grow functions as a micro-filter. Wash away what soil that you can, carve out a suitable pocket—without permeating the medium’s shell—and you have a nice home for your previously soil-based plant. The soil will not flow out of the STG to muck up your growing system. Except for the normal transplant adjustment, the plants take to it like ducks to water.

“

How to improve it?

STG cannot support larger, heavier plants on its own. Unless there is a stiffer superstructure around the medium (i.e. net basket, tomato cage, etc.), a heavy plant will topple in this medium. As plants grow larger, their root structure will firmly hold them in place. I don’t know that it’s possible, but a denser, heavier Sure To Grow would solve this.

Conclusion

For me, perfect growing materials utilize waste from other processes. Compost from kitchen scraps, manure from animals, and garden beds from old railroad ties are all perfect. So is Sure To Grow. Recycled plastic bottles transformed into a growing medium. Awesome!

No virgin rocks or wooly sheep were hurt in the writing of this article.

Happy Gardening!

Curtis

If you haven’t been following along, you might want to take a look at where they started. The flower clusters have been collected and dried. At this point it is suitable for storage, enjoyed by kitties, or in this case, seed collecting. If you look at the dried flowers closely, you can find the seed pods. Here is an example of a catnip seed pod. With a gentle touch, the pod opened, and three tiny seeds emerged. After opening the pods, blowing and shaking to separate the seeds from the chaff, I wound up with a nice pile of seeds, ready for planting. Peace, love and puka shells,

Grubbycup ]]> http://urbangardenmagazine.com/2010/07/catnip-seed-collecting/feed/ 0 http://urbangardenmagazine.com/2010/07/beginners-corner-can-i-grow-in-here/ http://urbangardenmagazine.com/2010/07/beginners-corner-can-i-grow-in-here/#comments Tue, 13 Jul 2010 01:03:12 +0000 Urban Garden Magazine http://urbangardenmagazine.com/?p=5039 I’ve asked myself this question countless times. Walking around a new property I hear the little voice inside my head weighing up each room, every nook and cranny, all with a view towards potential veg production. “Can I grow in here?” “How about in here?” “What about up there?” Yeah, I know, I sound like an obsessed little kid. But it’s not far from the truth. Growing indoors is more than just a hobby for me. It’s my life’s passion. So while the letting agent or realtor is trying to impress my wife with designer taps and garish bathroom ceramics, I’m speccing the place out for potential growing action. I mean, common boys and girls, do you really feel like you’ve moved into a new place until ALL the lights are on? Exactly.
Over the years the obsessive little kid’s voice has grown up, well just a little. Experience has taught me to ask a whole bunch of crucial questions when evaluating a potential grow space. I’m not talking about whether the wife will get mad if she returns home to find her walk-in wardrobe magically ‘transformed’ into a propagation station. She knew what she was taking on when she signed on the dotted line in front of the registrar! In fact, these days she doesn’t even complain, bless her. Maybe it’s something to do with the access to fresh homegrown salads she enjoys year round? In fact, it’s amazing what a steady flow of leafy greens can do for a relationship!
Anyway, lest we digress, let’s get one thing clear. When I ask, “Can I grow in here?” I’m not referring to obtaining permission from your spouse or anybody else for that matter. I’m talking about how we go about assessing the viability of a given space for indoor gardening. So, let’s dispense with the celebrity gossip and get on and do this!

1. Insulation

The better your indoor garden is insulated, the easier it will be to grow in it. Many indoor gardens suffer from excessive heat problems, especially during the summer months when ambient temperatures are considerably warmer. High temperatures can slow plant metabolism and stress your plants causing them to respond in unfavorable ways. This isn’t just a euphemism for death either. Many culinary herbs and lettuces will ‘bolt’ into premature flower and seed production if they are forced to endure prolonged high temperatures. Similarly, if nighttime temperatures drop too low this invariably stunts growth and bloom. Cold, poorly insulated rooms cause very slow growth, poor water and nutrient uptake, and low temperatures can cause further undesired changes in your plants – e.g. chili peppers will fruit prematurely if nighttime temperatures drop below 65°F (18°C). So remember, the better a potential grow space is insulated, the greater the “base level” of protection from extremes in ambient temperature and the less money and effort you will have to invest into controlling temperatures in your indoor garden. Is it really worth all the energy, money and time investing in a state-of-the-art cooling system to chill your grow lights in a ramshackle loft apartment in Los Angeles, or will it simply be cheaper and easier in the long-run just to move to somewhere more suitable? Now’s the time to ask yourself these questions!
Take a moment to think about the general characteristics of your house or apartment. What is it made of? Wood, stone, brick, concrete? How thick are the walls? What type of insulation has been used? Not sure? Ask yourself these questions: Does your home already get too hot in the summer, and is it a pain to keep warm during the winter? In either case – not a good sign! What about your indoor garden’s location within your home? Is it in a room at the top of the house that has an external wall facing the sun all day? Or is it cool and shady? Hopefully you’ll be nodding at the latter.
Insulation is measured by its R value. The higher the R value, the more effective the insulation. Some of the best insulation materials are:

• Blown in Cellulose Insulation – R3.70 per inch
• Fiberglass Insulation – R3.14 per inch
• Expanded Polystyrene – R4.00 per inch

Many growers report their greatest successes from gardens located in a cellar or basement. And there is a good reason for this – the amazing insulation qualities of the earth! So whether you are storing wine or growing food to accompany it, a basement can be ideal. (Just don’t do both at the same time!) Basements can be subject to high humidity, so you may also need to invest in a dehumdifier. Their subterranean location can make getting rid of spent nutrient solution more tricky than usual.

2. Ceiling Height

Look up. What do you see? Hopefully it’s a ceiling high above you, well out of reach. 8 ft ceilings are okay. 10 ft or more is a godsend for any indoor gardener – that extra air volume makes your life so much easier, believe. Not only do you have more height to grow climbing varieties of tomato, peas and beans but, once again, you will find your temperatures and CO2 levels far easier to maintain and control. Additional ceiling clearance means that you also have the option of raising the height of your grow trays so that your garden is easier to work in, with the additional benefit of making drainage / nutrient return easier to manage using plain old fashioned gravity alone.

3. Water

Your plants want a lot of things – some of them desirable, some of them essential. One thing they can’t possibly go without is water! Prior research into the water quality of the area will be useful. Generally, the softer the water the easier it is to grow with. Hard water can still be used to produce productive crops but a lot of growers now use RO machines to remove the carbonates and other contaminants. Indoor gardeners commonly use a large container such as a rain collection barrel to mix and store their nutrient solutions – often referred to as a reservoir or ‘res.’ Ideally this should be kept in an adjacent room so that your nutrient solution is not subject to the temperature changes in the growing area itself. Think about where you are going to store your nutrient solution and its location relative to your nearest water source. Running hoses across landings or up and down stairs is a pain and invariably leads to leaks and spillages. I’ve lost count of the amount of times a hose end has flopped itself out of a res, spewing water all over the floor. It’s a nightmare scenario! Filling up your res is a regular chore, so make your life as easy as possible with sensible planning and, ideally, a dedicated tap right above it. The less hose pipe in your life, the better! (My wife hates seeing hose pipe running from room to room!)

4. Drainage

It’s not just about getting water into your indoor garden. What about getting it out? Is there an easy way to drain your spent nutrient solution? Once again, it’s all about making life easy for yourselves! Most growers use a submersible pump and hose to drain their reservoirs. Some growers recycle their spent nutrient solution by using it on their outdoor gardens too.

5. Ventilation / Windows

Unless you are growing in a sealed room with AC and CO2 supplementation, you are going to need to install some sort of ventilation in order to keep on top of temperature, humidity and CO2 levels in your indoor garden. Many novice growers grossly underestimate their ventilation requirements. Remember, all that hot, CO2-depleted air needs to go somewhere. And then it needs to be replaced with cool, clean, fresh air of course! Simply pumping air out of your grow tent back, for example, into the same room it’s situated in does not count as adequate ventilation. We need to transport the old air well away, and keep the fresh air … well fresh!
Think of your ventilation in terms of input and output. In order to maximize your control over your indoor garden’s environment you should always spec the size of your output (aka extraction) inline fans bigger than your input. More air being pumped out than being pumped in creates a ‘negative pressure’ which ensures zero air and odor leaks and also increases the efficiency of your input fans. If you are using carbon filters with your input or output fans, remember to take into account their diminishing effect on their respective fan – often a 25% reduction factor is used but depending on the make and age of the filter it could be anywhere between a 10 – 30% reduction.
Extraction has the most positive effect on reducing temperature when it is removing air from the top of a room – as hot air rises. Ideally it should be vented out of the property to the outside world. As far as intakes are concerned, be aware of where you are taking your air from. Drawing ice-cold air direct from sub-zero temperatures outdoors and blowing it directly on your plants is not clever. It’s a far better option to draw air from a cool room in your home instead. Be sure to use a bug screen on all air intakes. Yes, you will have to spec up your fan by 10-30% to counter the increased air resistance, but at least you won’t be drawing bugs, mold spores and pollens into your indoor garden!

Size and Accessibility

Remember, you need space to work and get around in your garden. Ideally you should be able to access your growing area from all sides, allowing you to inspect all your plants with the same level of care and precision. Overfilling your garden, however tempting, will quickly turn maintenance into an onerous, back breaking exercise. Remember, your hobby should be a pleasure, and not a chore!

Pest Protection

All carpet should be removed from any space where you are planning to grow as it can harbor no end of pests and pathogens. If removing the carpet is not an option, you can lay down protective plastic sheeting. Remember, your indoor garden should be as easy as possible to keep squeaky clean. A laminate floor that is easy to mop is ideal. Air intakes should use a bug screen so that you don’t inadvertently suck bugs into your garden.

Next issue: Electrical Safety in your indoor garden – so important, we need to tackle this subject on its own!

So this leads us to the question: What’s the best way to take cuttings? Enter the aeroponic cloning machine! This units aims to provide the optimal environment for your cuttings in order for them to develop roots of their own. So here’s our guide to taking aeroponic cuttings and how to give your babies the ultimate in pampering!

First let’s get some basic concepts out of the way. The whole reason you want to take cuttings in the first place is because you’ve gotten hold of something really good and you want to preserve the genetics exactly. Yes, seeds are Mother Nature’s common way of perpetuating life on this planet, but even two seeds from the same pod or packet can produce very different plants. That’s because there’s always an element of genetic randomness in gene expression. If things didn’t change from generation to generation, nothing would evolve, so it’s all good in the hood! However, sometimes we don’t want things to change. Maybe we’ve happened upon a tomato phenotype that produces prolific amounts of sweet, cherry-like fruits, bursting with unusual amounts of sweetness and flavor. Perhaps it’s the only tomato your kids will touch? Or it might be the color of fruits and flowers that floats their boat. In any case, we’re going to assume you’ve already a plant that you wish to perpetuate.

You Love Your Mother, Don’t You?

Your mother (or donor) plant is a sacred thing. Look after her! Arguably, her health represents the health of your entire garden. If your mother plant is just “doing okay” legging up in the corner of your indoor garden then it stands to reason that all cuttings taken from her will just “do okay” too—in short, they will inherit her state of health and vigor. No amount of cloning gel and aftercare is going to erase a history of neglect.

The aim of the game with mother plants is to keep them in a perpetual state of growth. (You don’t want your mother plant to flower!) The easiest way to do this for many annual plants is to ensure that irrigation cycles are regular and your lights are kept on for 15–18 hours a day. Basically you ‘trick’ your plant into believing it’s in a perpetual summer! Ask your grow store for a T5 (6500K) fluorescent fixture or a 250–400W metal halide HID grow light. Both these lights have a great spectrum (high in blue light) which encourages lots of vegetative growth.

Ideally your mother plant should be grown in an ample-sized container (at least four gallons) or, for the ultimate in Mother-love, in its own dedicated hydroponic unit. The Waterfarm by General Hydroponics is a very popular choice for maintaining a mother plant as it encourages prodigious levels of growth with very little maintenance. It’s essentially a two-gallon grow chamber sitting on top of an integral four-gallon reservoir. The grow chamber is usually filled with well-washed clay balls, and a small pump drip irrigates constantly when the lights are on. (Some growers wait until 30–60 minutes after the lights come on before commencing irrigation.) If you are using any type of dripper feed system for an extended period, make sure you regularly check for salt build-up around the drippers. Take a close look at each hole and verify that all the dripper points are actually dripping when they should be! Some growers use a small drill bit to increase the size of the holes in the dripper ring whereas others prefer to flush periodically with plain water or a low EC nutrient solution. Always use a grow formula for your nutrients but don’t over-do it (keep your mother plant as small as possible)—excessive levels of nitrogen can inhibit root development in cuttings.

Keep your mother well trained. Make sure she is regularly pruned to maintain a manageable size. As you take more and more cuttings from your mother plant, you will notice that she becomes increasingly bushy. If she becomes too bushy, start a new mother plant with a fresh cutting. Most growers tend to replace their mother plants every six months or so.

Taking cuttings is an easy concept to grasp. You’re effectively cutting off part of a plant, adapting the environment to enable it to survive without a root system, and then encouraging it to form roots of its own. Hey presto, you have another plant! A cutting is a 100% genetic copy of the mother plant, so it’s a great way of ensuring consistency from crop to crop.

Just for the record, let’s go through the (very simple) process of taking a cutting. We’ll keep things brief as, no doubt, most of you know the drill. It’s not so much the actual taking of the cutting we wish to focus on, it’s looking after them afterwards! Anyway, here we go:

How To Take a Cutting

Stem cuttings are by far the most common type of cutting that gardeners take. It involves removing some stem from a plant that contains a healthy growth tip. We’re using tomatoes for this example but this method applies to nearly all soft-wood plants.

Step 1 – Take a clean scalpel or a very sharp knife and remove a healthy looking branch from your mother plant. The sharper the blade, the cleaner the cut and the less tissue damage around it—meaning less chance of disease.

Step 2 – Remove any excess stem. Many grow guides will tell you to take a cutting at a 45 degree angle, to increase the surface area of the exposed cutting to rooting stimulators. At risk of being contentious, this really is not necessary! I actually prefer to take a ’squarer cut’ because the cut part of the stem is less susceptible to damage.

Step 3 – The more foliage on your cuttings, the more ‘life’ it has to support. It makes sense, therefore, to remove any excessive foliage. Yes, some leaves need to remain but you’re really after small, manageable cuttings that aren’t going to crowd out your propagator or cloning machine. Trim the tips of larger leaves so that the cutting is no larger than the space it is going to be given in your cloning machine. Less foliage on your cuttings makes life easier because there are fewer leaves for the cutting to support through this acutely stressful period in its life! Just as importantly, small cuttings don’t overlap each other so much, which significantly reduces the risk of mold.

Step 4 – Your cutting should look something like this. Most growers aim for cuttings between three and five inches from top to bottom. The next step is to dip your cutting into some rooting stimulator. Though not essential, rooting times will be shorter, decreasing the chance of mold or stem rot. Several compounds can be used to promote the formation of roots. They work by signaling the activity of plant hormone auxins. Among the commonly used chemicals is indole-3-butyric acid (IBA) used as a powder, liquid solution or gel. There are also cloning products on the market that use only natural ingredients. Whichever route you take (pun intended, sorry), don’t dip your cutting straight into the jar the product came in as this can lead to contamination and a far less effective product. Instead, pour a small amount into a shot glass and dip into that instead. Clean the shot glass and your blade regularly, particularly if taking cuttings from more than one mother plant. You don’t want to be transferring viruses between plants!

Okay, so now you have a freshly-taken, foliage-trimmed cutting, that’s been dipped into rooting gel or powder. It’s time to fire up your cloning machine! A timely word of advice: it’s important not to dawdle when taking cuttings! Remember, every second counts. After all, if you leave a cutting on your kitchen table, it will dehydrate and be well on the way to dying in a matter of minutes. So the sooner you can get your cutting into a propagator or cloning machine, the better. Preparation is key, especially if you are taking lots of cuttings.

Aeroponic Cuttings – Pros and Cons

Pros

1) Quicker, more vigorous rooting
2) Cleaner, so less chance of disease
3) Less maintenance
4) Reduced risk of drying out or wet / dry stress
5) No need to purchase or prepare growth media.
6) More flexibility when you choose to use your cuttings.
7) Larger cuttings can be more readily supported in aeroponic cloning machines.
Aeroponic cuttings tend to be a little hardier as they haven’t rooted inside a propagation dome.

Cons

1) Extra care needs to be taken when transferring to loose fill media.
2) Aeroponic cuttings are more sensitive to changes / extremes in temperature.
3) Increased start-up costs—unless you fashion your own machine!
4) Risk of power-cuts! A few hours of no misting can damage or kill your clones. Consider using a UPS battery back-up if power cuts are common in your area.
5) Pumps (or: The pump) and misters can be a little on the noisy side. Nothing too severe, but you wouldn’t want them in your bedroom.

Aeroponic Cloning

Fresh tomato cuttings inserted into a cloning machine. Foam disks hold the cutting firmly but gently in place.

An aeroponic cloning machine allows you to root your cuttings without the expense of buying media or the time necessary to prepare it. Typically, a submerged pump drives nutrient solution into low pressure misters. Amazingly, no humidity dome is required because the cuttings are still able to uptake any moisture they need directly from the mist. As with all equipment you use for taking cuttings, make sure your cloning machine is kept clean! Fill the machine to the indicated level with water that is at 65–68°F (18–20°C).

This low pressure mister attaches directly onto a submersible pump, creating an even mist for the cuttings. Be sure to install it so the misters point upwards.

There’s no need to add any nutrients because your cuttings don’t have roots yet! Saying this, some growers still prefer to add some hydroponic nutrients at this stage, so that as soon as the cuttings develop roots of their own, they have some immediate food available.  Hydroponic nutrients are preferable over organic nutrients as they can be immediately assimilated by your cuttings and they don’t foul up your “res.” Many growers use a very dilute version of their standard ‘bloom formulation’ because the phosphorus encourages further root development. Others prefer to use a specialist product for young plants so that the ratios of micro and macro elements are kept in balance. If you add nutrients, adjust to pH 6.0–6.3 with dilute phosphoric acid and shoot for an EC of between 0.4 and 0.6.

Room Environment

As mentioned earlier, aeroponic cloning machines don’t need humidity domes. This means it’s absolutely crucial to have your room’s environment dialed in. Your cuttings will be happiest when located in a room kept around a steady 70°F (21°C.) Try to keep room temperatures below 75°F (24°C) as excess heat just adds transpirational stress, and more stress is the last thing your cuttings want! Aim to keep the nutrient solution at 68°F (20°C); any warmer will decrease levels of dissolved oxygen in your nutrients and increase the likelihood of pathogens and stem / root rot. If your room (or nutrient solution) is too cold this will slow metabolism, shock your cuttings and inhibit that all important root development. The submerged pump will heat the nutrient solution slightly so you definitely need to keep an eye on nutrient solution temperatures. Use a nutrient thermometer to keep on top of things. If you find that the pump is warming up your nutrient solution excessively, try relocating your cloning machine on to a stone floor, lower ambient temperatures in your room if you can, or run the pump on a timer, five minutes on, five minutes off, rather than letting it run constantly. Relative humidity levels should be at least 65%. If the relative humidity in your room is less than this, you should consider misting or using a propagation dome to help increase the relative humidity directly around your cuttings.

Light Levels

Cuttings don’t require much light; in fact, high light levels are to be avoided. Remember, you want your cuttings to concentrate their energy on creating roots, not coping with an intense growing environment—that will come in time! A pair of two-foot, 55 watt, T5 fluorescent tubes hung five to eight inches away is more than enough to keep 30 or 40 cuttings very happy. Other growers will simply relegate their cloning machine to the corner of the veg chamber so that it is in the diffused light of their metal halide grow lamps. Just be sure the lights are not too intense and keep them on for 18 hours a day. Some growers prefer a 24-hour lights on approach as it makes temperatures easier to regulate, but all plants benefit from a little time out. There’s no need to overwork them! Make sure temperatures do not drop too low during the lights out period. Use a Min/Max thermometer and a thermostatically controlled heater if required, but don’t blow warm air directly on to your cuttings … ever! This will dry them out and cause them untold stress.

Insert each cutting into the center of the foam discs supplied with your cloning machine so that at least two inches of stem dangles in the misting chamber below the lid. Remember, there should not be any leaves in the misting chamber—just bare stem.

Day 1 – Settling In

Day 1 – Freshly inserted cuttings viewed as they are seen from the misting chamber.

Don’t be concerned if your cuttings wilt a little immediately after insertion into your cloning machine. They should perk up within an hour and return to looking pert. If they continue to appear limp you should try applying a very light spray with water or a dilute foliar solution with a wetting agent to help the moisture cling to the leaves. Amazingly no humidity dome is required when using aeroponic cloning machines as the cuttings are still able to uptake moisture from the misting chamber—even without roots! Your cuttings will thrive in a well ventilated but not drafty space. The last thing you want is a fan blowing on them. You shouldn’t have to do anything for the first few days—just keep an eye out for any wilting. If any cuttings don’t look happy, it’s not too late to replace them.

Day 3 – Roots start to develop

Day 3 – Cuttings start developing root calluses.

Cuttings tend to root faster in aeroponic cloning machines. It won’t be long until you see the beginning of root development. Typically this starts with the formation of small white calluses on the stem. Keep an especially watchful eye over your cuttings during the next few days. Roots should be bright white. If you observe brown or discolored roots, this could be a sign that your nutrient solution is too warm. If you haven’t done so already, it’s definitely a good idea to add some mineral nutrition to your cloning machine’s reservoir at this point as your cuttings can certainly derive benefit from it. Some growers change out the res at this stage.

Day 7 – Root Explosion!

Just 7 days after being taken, these cuttings are already bursting with root development.

With such prolific root development, it’s tempting to think the job is done, but it pays to be a little more patient before removing your cuttings from the cloning machine. This is just the ‘first generation’ of roots.

Day 8 – Secondary roots begin to develop

Day 8 – We can see the first signs of secondary root development.

As secondary roots begin to emerge, we are fast approaching the time when the cuttings will leave the cloning machine and begin life as young plants!

Day 10 / 11 – Ready and Raring to Go!

The cuttings are ready!

Lots of secondary root development and root hairs too. They are ready for transplanting.

The emergence of more secondary roots and root hairs is a sure sign that your cuttings are developed enough to handle life outside of the cloning machine. If you’re not quite ready though, don’t worry; the cuttings will be quite happy to bathe in their nutrient mist for days, even weeks if required! Just be sure to change out the nutrients once a week and keep an eye on pH levels. If roots become very long you can always trim them —they won’t mind!

Transplanting

A net pot is an ideal next stage for an aeroponic cutting. This gives you a chance to establish your cutting in the growth media of your choice. One common question about aeroponic clones is how to handle transplanting them into a pot of loose-fill media or hydroponic system. For instance, there is a common myth that aeroponic clones don’t do well in soil or coco coir. This is simply not the case; you just need to take care. Ensure your chosen media is at room temperature and fairly moist. Also, remember roots hate light, so be kind to your cuttings and transplant them away from bright lights. Partially fill the pot with media, make a hole just big enough to insert the rooted cutting, and gently back fill around it so all the roots are covered and your cutting is well supported. They will need a few days to adjust, so don’t go whacking them straight under your 1000W metal halides just yet. Ease them in gently under a 6500K T5 fluorescent or a 250W metal halide. Some growers foliar spray with sea kelp products which help to reduce stress levels. Other growers use a Victorian Bell Cloche to increase humidity levels for the first few days as the cuttings settle in.

PHOTO CREDITS: OUR BELOVED GRUBBYCUP

AEROPONIC CLONING FAQ

Here are some of the most common questions about aeroponic cloning:

1) What kind of water should be used initially to fill the res? Is regular tap ok? Or should I use distilled? Any need to pH adjust the water initially?

Regular tap water is typically fine in most major areas. It’s what I always recommend trying first. Distilled water should NOT be used, as it is so stripped of any type of mineral content that it pulls important minerals from the plant tissue hindering the initiation of root development. I often recommend users run their system without cuttings in it for the first 24 hours if they have the time. This allows them to check what their temps will be and allows some time for pH stabilization. Water should be pH adjusted after any types of solutions are added and adjusted again after cuttings have been inserted. Fill the cloning machine as high as you can so that the water level is just below the misters. The more water that is in the res, the more stable the pH and temperature.

2) Do you recommend adding anything to the water?
Yes. Use a rooting stimulator – check the label but 1 teaspoon per gallon is a general guide. Also, consider adding a silica product – this will assist in building strong cell walls and protect against bacteria etc.

3) What about adding some mineral nutrition? Should growers wait until they see roots developing? How much? And what sort of strength / pH?

I typically add nutrients only after roots have gotten between 3-4 inches in length. It’s the grower’s preference whether they go mineral (hydroponic) or organic, however I find regular hydroponic nutrients usually keeps the reservoir cleaner. I usually stay between 400-500 ppm for new clones after root development. pH between 5.8-6.3. I prefer 5.8.  I’ve also noticed that even without additives of any kind, the pH of tap water will have a tendency to rise over the course of 24-48 hours. To compensate for this, I adjust my initial pH down to approximately 5.2 because I know the pH will slowly rise somewhere close to between 5.8 and 6.3. This is an acceptable range for getting quality results. I keep the closest eye on my pH during the first 24-48 hrs. If the pH needs to be adjusted again later on, do so, but it usually stables out after the first couple adjustments. If you are not sure if you’ve got an accurate pH reading, I highly recommend getting a quality digital pH meter.

4) Veg or bloom nutrients?  Something with phosphorus (for rooting) and nitrogen?  If using GH 3-part for instance, what ratios would you use?

As long as I’m taking cuttings from a healthy Mother plant, I don’t use nutes for cloning. A cutting is developing roots because it’s searching for food. If you try to feed something that doesn’t have a mouth yet, you’re defeating the purpose. Cuttings root perfectly fine with some IBA’s and Vitamin B-1.

5) Any additives?  Either in the res or foliar?

This is a tricky topic because there are so many different additives on the market. I can’t recommend just one. We are introducing a brand new product to the market right now called EZ-CLONE Clear Rez that is designed to keep all of the internal workings of your cloner free from pathogens and promotes prolific white root growth. We’ve been testing it for over a year. It’s amazing…

6) Can you explain how root-less cuttings are still able to uptake water, with no need for humidity dome?  We’ve seen it with our own eyes, just wondered if there’s a scientific explanation.

The plant tissue still absorbs a sufficient amount of moisture for the cutting to sustain itself upright. Roots develop because the cuttings are searching for food. Humidity domes are NOT necessary with aeroponic cloners. In fact, I suspect domes help to promote airborne bacterias such as powdery mildew and prevent the cutting from transpiring naturally.

7) What are the general signs that a cutting is ready to leave the machine?

It depends what medium you’re transplanting into. I prefer to let the roots get 6-8 inches in length before transplanting into soil, coco, hydroton clay rocks, or other aeroponic systems.
The longer the roots, the better chance of your cutting surviving after its been transplanted.

Any danger signs to look out for? If root tips are slightly off color, is that okay, or a bad sign? When are nutrient temperatures definitely too high?

When res temps get above 80 degrees, cuttings are more prone to pathogens and bad bacteria. Slightly off color can be ok. If you start getting greyish/brown slime cover the bottom of your cuttings, it’s time to take precautionary measures.

9) Any general tips for transplanting aeroponic cuttings into media?

The longer the roots, the better. It’s always ok to cut excessive root growth off with sterile scissors if you’re trying to transplant a cutting into a rockwool cube or other similar medium. Most people don’t understand that this will NOT kill the cutting. Just make sure scissors are clean and always be delicate when transplanting.

10) Have you heard of growers using cloches / domes to reduce transplant stress?
Only when cuttings come from cloning methods where domes were used. When they’re cloned without domes, they transplant into domeless mediums MUCH easier.

11) Any other golden rules / tips / tricks?
We’ve kept our water temp coolest and actually saw slightly better results when putting the pump on a half hour on/ half hour off timer…a little new found info.

12) Is it necessary to change out the reservoir during one cloning cycle?
No, if everything is in proper working order, you should be able to continue using the same water for 4-6 weeks.

Everest Fernandez

• There are plenty of fish in the pond, and plant nutrients are a known result of fish.
• The spring algae bloom is prolific (more on that in a minute).
• The system is already supporting existing plants very well.

Fight it.

or

Don’t fight it.

Gentle Reader, I suggest you just learn to accept that the pond is going to look a bit green for a while once a year. After checking the piggy bank, and getting threatened with being turned over to the ASPCA if I don’t start feeding it a little something once in a while, I made the executive decision that this was going to be a budget minded enterprise. So perhaps a future version will include my aspirations to extend the deck, but for now, a couple of 4″x 4″s and a re-tasked wooden frame will form the base. Wicked pots sit on the platform. They will be top watered until the roots are established, then they should be able to pull pond water up the wick, and finally, send roots down into the pond itself. This is where I got even with the piggy bank. The piggy bank now exists only as an abstract concept of anti-existence. I bought two inexpensive “mini-greenhouses” for $30 US each. There are several things I like about these racks:

• They are light enough to sit on the wooden platform.
• Easy to put up.
• Great to scavenge parts from.
• The shelves make for a nice training screen.
• They were cheaper than what it would cost if I built it. I tend to get carried away.

This, Gentle Reader, is my process. I make a model, and learn from it. Then another, and another, sometimes I start making them a little bigger…

So when I take the plunge on expensive things like the solar panels and water pump (I want to use to pump the water up to a reservoir, so the only “house electricity” it uses is a valve on a timer), I can feel confident that the rest of the design will work.

Peace, love, and puka shells,
Grubbycup ]]> http://urbangardenmagazine.com/2010/05/pond-hydroponics/feed/ 4 http://urbangardenmagazine.com/2010/04/irrigation-for-rockwool/ http://urbangardenmagazine.com/2010/04/irrigation-for-rockwool/#comments Wed, 14 Apr 2010 01:06:48 +0000 Urban Garden Magazine http://urbangardenmagazine.com/?p=4486 Developing Irrigation Strategies for Maximum Productivity

Rockwool is a mainstay of commercial hydroponic growers – and for good reason. It takes up a minimal footprint and, when used correctly, yields like crazy. We asked Dr Lynette Morgan, a world authority on hydroponic vegetable production, to give us some expert advice on growing tomatoes in rockwool. There’s LOTS to be learned here as Dr Morgan takes us through how to develop irrigation strategies for your particular growing environment.

Rockwool, also known as stone wool or mineral wool, is the most widely used substrate for the commercial production of hydroponic tomatoes. It is also a great tool for smaller growers who can benefit just as much from its use in a range of different systems and situations. While rockwool is relatively easy to set up and use, it does require some monitoring and irrigation adjustment to make the best of its ability to hold high levels of moisture and aeration at the same time.

Rockwool originally started as a thermal insulation material in the construction industry: its lightweight but highly aerated nature helps keep heat in buildings, while being easy to handle, cut and install. However, towards the end of the 1960s, trials were carried out in Denmark to test the possibility of using stone wool as a substrate for plants. Things went well and since then rockwool as a growing media has seen some continuing development of the substrate and the tools used to manage it.

Rockwool comes in a range of sizes from propagation cubes to large slabs and even a granulated product.

Rockwool is manufactured by melting basaltic rock and spinning this molten mix into thin fibers which are then cooled by a stream of air. Although rockwool is a man-made substrate it is essentially made from rock and considered by many to be a natural product. Grodan dominates the rockwool market world-wide and is the most common brand used by large and small hydroponic growers alike. Grodan rockwool is highly advanced and is not a single product – growers can select from a number of different Grodan rockwool types such as `Grotop Master,’ `Grotop Master dry,’ and `Grotop Expert,’ all of which have slightly different properties and uses. `Grotop Master Dry,’ for example, maintains a slightly drier root zone and is used by tomato growers to steer crops away from overly vegetative growth. `Grodan Classic’ is used for multi-year use, while `Grotop Expert’ is designed for ultra quick root growth and development. Along with these product differences, rockwool of many brands comes in a huge range of sizes from tiny propagation plugs for seeds to larger cubes for cuttings, mega sized cubes for large plants, a wide range of slab sizes, and as a granulated product as well.

Setting up to grow with rockwool

1. Sit the rockwool down

Whether you are using the standard rockwool growing slabs, large cubes, or even pots of granulated rockwool, basic preparation is important. Slabs and cubes in particular need to be on a flat, even surface as any indentations will cause the material to sink and create pockets of unwanted moisture. Next, realizing that nutrient solution will be draining from holes cut in the slab’s plastic wrapper or from the base of cubes, some consideration for drainage of this solution away from the slab is important. There is no point in having well placed and made drainage holes if the solution can’t be channeled away from the slab and the material ends up sitting in a pool of stagnant waste nutrient. Many small hydroponic systems on the market these days designed for use with rockwool have trays and channels designed to do just this and these are a good choice for inexperienced growers.

2. Settle the rockwool in

Rockwool, whether it is slabs, small propagation blocks, or large growing cubes, needs to be prepared correctly by fully wetting the substrate before use. Some growers like to adjust the pH of their water to 5.5 before wetting up rockwool, but generally for small systems it’s not necessary with good quality brands (unless you have a very `hard’ water supply in which case acidification of the water before making up any nutrients would be a good idea). The rockwool should be fully saturated so that all of the material is wetted and then left to drain. Some growers pour water into the rockwool slab before the drainage holes have been cut to make sure everything has had a good drenching, while others just pour water on or run the irrigation long enough for saturation to take place.

3. Remember the holes

Rockwool slabs need drainage – holes or slits should be cut in the plastic sleeve the material comes in. Several cuts are required along the base of the slab. Granulated rockwool should be placed into containers or pots with plenty of drainage holes in the base.

4. Irrigation programs

The most common way of applying nutrient to rockwool slabs or large blocks is with the use of dippers. A simple drip irrigation system should use a dripper with a capacity of 2 litres/hour, with one dripper per plant. Because a standard rockwool slab may hold four tomato plants, four drippers per slab are required, which also means that if any one dripper becomes clogged, the entire slab will still be getting enough irrigation until the problem is fixed.

Developing an Irrigation Strategy for Rockwool – The Moisture Gradient

Rockwool is the most widely used substrate for hydroponic tomato production.

The irrigation program for any hydroponic plant is vital for successful growth, development and optimal yields. The most common problem experienced by smaller or new growers is over watering, and usually the grower is totally unaware that it is their irrigation program causing problems with plant growth. Flushing vast amounts of nutrient solution through the root zone in a substrate-based system often equates to plant murder – more is not necessarily better when it comes to nutrient application. This type of mistake is easy to make. After all, many new growers get enthused about hydroponics after seeing a well-run NFT or other solution culture system and assume that plants are more than happy to grow and thrive in a flooded root zone environment. However, solution culture and substrate systems are completely different and need to be managed in different ways for the plants to get the optimal root zone conditions they need. In NFT the roots should never be flooded: they sit in a very thin film of nutrient flow (2-3 mm or about 0.1″ deep), hence the roots have moisture at the base of the root system, but many of the other roots are sitting up in the moist air, accessing all the oxygen they need without being submerged. In a rockwool slab the plants are in a similar situation – at the base of the slab there is plentiful moisture, usually at media saturation levels, while in the upper layers of the rockwool slab the roots are in drier conditions and hence have access to plenty of aeration and oxygen for root uptake and respiration. It is this moisture gradient from the top to the bottom of the rockwool material that makes it such a good substrate. At the same time, growers who are not aware of this property can make the mistake of thinking the rockwool is too dry on the surface and over-irrigate their plants despite having plenty of nutrient solution being held deep down in the root system. Rockwool growing media, when being irrigated correctly, should not sit in a pool of nutrient and be completely saturated from top to bottom like a sponge. It is essential that the rockwool is allowed to completely drain so that excess nutrient leaves the slab or cube under the pull of gravity after being applied– in doing so, fresh air is drawn into the top layers of the material, providing fresh oxygenation for the root zone. By allowing the rockwool material to drain freely, over-watering becomes more difficult, although vast amounts of nutrient drainage from the base of rockwool slabs or cubes is not an ideal situation either.

Setting up an Irrigation Program

Obviously the amount of nutrient required is going to depend on factors such as the size of the plant, the growing conditions, light, temperature and, in particular, humidity, which drives plant transpiration and water uptake. So the irrigation program is going to change as the plants develop. Also an irrigation program needs to be developed and adjusted by each grower for their particular system, environment, and set up and this has to be monitored and adjusted as required. Just following guidelines for the amount of nutrient to apply at certain times will eventually lead to over or under-watering, as each plant and situation is different when it comes to nutrient and water requirements.

Commercial hydroponic rockwool growers have some good tools for fine-tuning their irrigation. The Grodan water content meter allows growers to measure the water content, EC and temperature in the rockwool slab root zone using hand-held meters or a continuous monitoring system hooked up to the computerized irrigation program. However, these sorts of high-tech tools are not often used by smaller growers and a successful irrigation strategy can be put together with just observation, some innovation, and a little time.

Remember the Moisture Gradient

Rockwool propagation cubes and slabs are designed to be used together to minimize root disturbance. Excellent moisture holding capacity and good aeration of the root zone are features of rockwool substrates.

Irrigation of rockwool is a little different to other solid substrates because of the way the material is manufactured to have just the right degree of moisture gradient, and because it does give quite a limited root zone for plants that eventually grow fairly large. For this reason, rockwool is best irrigated with short, frequent applications of nutrient, with just enough at each irrigation for the rockwool to reach ‘field capacity’. Field capacity is a term that means the substrate has drained fully but is still holding a good level of moisture for the plant roots to access until the next irrigation. At each irrigation, there should be some drainage from the rockwool material. However, this doesn’t need to be excessive. Even in closed systems where the drainage solution is being collected and reused, it pays not to over-water and not to run the irrigation continuously. Having around 10-15% of the nutrient solution fed to the plants, drain from the slab at each irrigation is considered to be optimal. This amount of drainage of solution flushes fresh nutrient solution right through the slab without too much wastage and usually keeps the EC in the slab fairly stable.

When rockwool is irrigated and allowed to drain naturally, it will then contain 80% nutrient solution, 15% air pore space and 5% rockwool fibers. A typical rockwool tomato growing slab actually holds around four gallons (about 15 liters) of nutrient solution immediately after irrigation, despite the drainage holes allowing free drainage of excess solution. Four gallons is a good reserve of moisture for four plants, so drying down to wilting point could take a long period of time for small plants.

How much solution should be given at each irrigation?

Having a drainage collection tray or channel under each slab allows growers to see how much drainage they are getting after each irrigation (even if this has to be poured off and measured in a jug) and the irrigation program can be increased or decreased to keep this at the 10-15% level. By doing this, the amount of solution to be given at each irrigation can be worked through and adjusted as the plants grow. Keep cutting back the irrigation amount until only 10-15% of the solution volume applied drains from the slab, and then the amount of irrigation has been fully adjusted for.

How often should nutrient be applied?

Rockwool needs small frequent irrigations, particularly under hot or low humidity conditions when the plants are taking up a lot of water. However, the frequency of irrigation can be as low as once per day (or every other day) for small plants under cool conditions, to over 10 times a day for large plants in a hot or dry environment. It can be hard to judge just how much moisture the rockwool material may be holding at any one time to determine when to irrigate. Smaller propagation blocks and even larger cubes can be gently picked up – the weight will soon tell you if the cube is saturated (it will be comparatively heavy and moisture will drip from the wet base), or whether it has dried out considerably, in which case it will feel very light (compare an unused dry cube to one in use). Rockwool is an unusual material in that, even when the slab has lost 50% of its moisture to plant uptake, the plants are still able to very easily keep extracting water until the slab is almost completely dry – so plants in rockwool can’t get water stressed until the rockwool is almost completely dry, by which time the cube or slab has become much lighter in weight. For granulated rockwool in pots or containers, a similar method can be used, either by gently lifting the pot to see what the weight might be (a light pot is a dry pot) or by a light tap or kick: if the pot moves, the rockwool has become quite light and potentially too dry.

Another method to try and gauge the moisture status of the rockwool and how often to irrigate is to carefully remove a small piece of the wrapper plastic and examine the moisture gradient of the slab from top to bottom. Like all growing media, moisture in rockwool can be gauged manually. Lightly touching or pressing the rockwool at the base of the slab will soon determine if there is still a good level of nutrient held in the base of the slab or whether it has become too dry. The top and middle layers of the slab should always appear drier than the base where the reservoir of moisture is naturally held, so only the base of the slab should be checked. Even if the top of the slab appears to be dry, this is not important as the moisture gradient has been designed to give these sorts of root zone conditions – only ensure the base of the slab has sufficient moisture.

This process of working out how much moisture is still in the rockwool material is not something that needs to be done for long. Growers will soon become quite skilled at working out their frequency and amount of irrigation for each stage of plant growth and may only need to do this for their first crop provided growing conditions remain stable. Other times when it might be important to have a quick check of the amount of solution drainage or amount of moisture in the slab is when conditions suddenly change – addition of more grow lamps, sudden changes in temperature or humidity, or rapid growth spurts can all change the irrigation requirements of the plants.

Generally, good brands of rockwool are quite forgiving compared to other substrates – the material is naturally well aerated and doesn’t suffer the compaction issues that some substrates do during the life of the crop. It does hold high levels of moisture, so the chance of drying out is not as severe as it might be with other substrates and being sterile gives young plants, seedlings and cuttings an advantage as well. The irrigation program and water holding capacity of the substrate depends on the fiber density and arrangement, which can differ from brand to brand.

More Advanced Irrigation Practices

With tomatoes and similar crops, growers have the option of using the EC and moisture content of the rockwool slab to help ’steer’ the plants into either more vegetative or ‘generative/reproductive’ growth, depending on what is required. Drying the slab back between irrigations and allowing the EC in the root zone to increase pushes tomato plants into a more generative or reproductive state with less leaf growth and more assimilate being directed into the fruit. A higher level of moisture maintained in the rockwool and a lower EC pushes the plants towards more lush vegetative growth. Skillful growers use these techniques to direct their crop and control leaf, flower and fruit growth at different times, and rockwool is a great substrate for this sort of control via the root zone.

Other Rockwool Tips

EC Levels and Management

Checking the EC in the root zone is important with rockwool just as it is with any media. The EC of the nutrient solution in the growing substrate changes as plants extract different ratios of water and nutrients from the root zone. The EC in the drainage solution coming from the base of the rockwool cubes or slabs is the best indication of the EC the plants are actually experiencing in the root zone. As a general rule, the EC in the drainage solution should be the same as or only slightly higher than that applied to the plants in the feed solution. If the EC is becoming much higher in the drainage than what was fed to the plants, then the EC in the feed solution should be dropped back – this is common under hot growing conditions when the plants might be taking up far more water than nutrients, hence concentrating the nutrient solution.

Rockwool Reuse

Rockwool for tomato crops can be reused – some commercial growers get many successive crops from rockwool slabs by steaming these after the plants have been removed and then replanting. Smaller growers can also do this – a few slabs can be heat treated by pouring hot water through them. Solarization is also possible, as is using chemical disinfectants, although care should be taken to rinse the rockwool well with plenty of water after using these. Commercial Grodan users have the option of the Grodan recycling service, which picks up the used slabs and recycles them into new product. However, smaller growers with just a few slabs of used rockwool can recycle the material by shredding it and reusing it as a growing media, as a component of potting mixes, or by incorporating it into outside soils and gardens.

Real World Rockwool Q&A

Q: What pH should I adjust the nutrient solution to and how do I monitor and adjust accordingly? For instance, keeping the tank pH at 5.8 and the run-off at 6.0 is perfect, but what happens if the pH starts to come back higher or lower than expected? What could / does this mean? And what should be done to correct it? How much should a grower raise or lower the pH of the tank with pH adjusters – when does a situation become ‘too extreme’ to use pH adjusters?

A: There are many factors that affect pH in the nutrient: some are normal like plant uptake and nutrient formulation salts (NH4 in particular), and some are not so good, like root disease. Water plays a big role and can range from very hard to very soft and hence needs to be handled differently depending on what a specific grower is dealing with. Chemicals for pH adjustment are also a huge topic! The nutrient solution pH is usually optimal at around 5.8 – 6.0 for commercial tomatoes; however, for small systems pH in the range of 5.5 – 6.8 is usually fine and having tight control at 5.8 is not necessary. The main problem with pH is with growers who might have a `hard’ water source, which is highly alkaline. In that case, acidifying the water with acid (nitric or phosphoric) before making up any nutrient will give better and longer term control of pH swings (in any growing media). pH should not need to be raised in most situations unless the water supply is very acid: in that case, potassium hydroxide should be used.

Q: I understand that rockwool can be prone to salt build-up if you don’t know what you’re doing like the commercial guys. Most hobby rockwool growers I have talked to flush either one day a week, throughout the whole grow and bloom cycle, or when they dump the res. (They will commonly give their plants 24 hours of either very low nutrient solution (if so, what EC?) or pure water, or even pure water with a product like GH Flora Kleen. What do you think of these flushing techniques? Do you have any better advice?

A: Rockwool is actually one of the better media for preventing salt build up as it tends to be drip irrigated from above and not bottom watered like with ebb and flow. Flushing is another subject that really needs a whole article to cover the theory, practice and problems with it. Flushing with straight water after a plant has been sitting at normal or high EC is not recommended: it causes the plant cells to suddenly take up huge volumes of water (because the osmotic pressure has been dropped in the root zone). This can cause cells to burst and create major physiological problems – splitting of tomato fruit is one common one; many other fruits and vegetables do the same. Even low strength nutrient can do this. Any changes in EC in the root zone should be done slowly (i.e over days), so a gradual dropping back of the EC over a few days should be done rather than flushing with water. Or better still, don’t let EC build up in the first place!

Q: What is the disadvantage of watering rockwool for a minute and getting 50% run-off in a closed system with adequate drainage, as opposed to watering for a minute and getting, say, 15% runoff? If you are only achieving 15% run off, is it not the case that the rockwool is already fully saturated and any additional runoff will just wash out the excess salts more thoroughly? In short, how difficult is it to over-water rockwool? I also can’t see what the problem would be for the plant if more run-off was created unless, of course, you were irrigating for several minutes to achieve this much run off, but even then surely the plant won’t feel any effect having its roots flooded for, say, 10 minutes, then allowed to drain freely?

A: Rockwool is a media which has been specifically designed for commercial growers who aim to have the recommended 10-15% run-off with the slabs spending as little time as possible at saturation levels – when doing this, the structure of the rockwool has been manufactured so that the root zone will remain at the correct moisture status which is why it is recommended. Also, with rockwool systems, the feed nutrient should be applied so that ‘excess salts’ don’t occur and therefore don’t need continual flushing. If the EC is getting high in the drainage solution, drop it back in the feed solution and/or increase the frequency of short irrigations. Rockwool, like any media, can be over-watered if flooded and is best kept below the saturation level for balanced growth.

Q. What’s the scientific explanation behind the influence that irrigation strategies have (or, to be more precise, the levels of moisture in the root zone) on generative / vegetative growth? Is this peculiar to tomatoes or is it applicable to other species?

A. Crop ’steering’ as it’s called is a technique used by commercial growers to manipulate the natural growth pattern of the plant. It’s widely used by skilled growers of tomato crops, but also on capsicum and many other plants as well. It’s quite a complex topic as there are a number of tools a grower can use in a controlled environment to direct the growth of the crop – commercial growers will use a combination of DIFs (day/night temperature differentials), EC, CO2, moisture control in the root zone and directional heating (i.e. directing heat towards the fruit or tops of the plants) to manipulate the growth of the plant. Different techniques force the plant to send the assimilate produced in the leaves into flowers/fruits when required or direct the plant back to some more vegetative growth if that was what was required. Various temperature techniques are sometimes used to keep seedlings or older plants as short and compact as possible (i.e. prevent stem elongation) and to get the plant to hold back on the production of overly large, succulent leaves. Commercial tomato growers use tools such as measurement of stem diameter to determine if their plants are getting overly vegetative or too generative at certain times of the year. The basic scientific explanation of why this works is that when a flowing plant encounters ’stressful’ conditions such a drying back of the root zone, high EC, high light and temperatures, it triggers a response – the plant wants to hurry up and flower, and to set seed to make sure it reproduces before the harsh conditions can kill it. We sometimes see this effect on lettuces which, under high light, temperature and moisture stress, can flower (or bolt) while the plant is still only a seedling and far from maturity. A plant with plenty of moisture under no particular stress is happy to go on producing a lot of large leaves with no hurry to set fruit and seed, which is great for vegetative crops such as lettuce but not so much with fruiting crops like tomatoes and capsicums. The ‘controlled stress’ commercial growers use to direct plants into more generative growth is often via the root zone because with Grodan rockwool very precise control of moisture content in the substrate can be controlled – particularly with the use of the Grodan moisture meter. And in hydroponics, control over EC is also fairly easy and precise. For this reason, Grodan Rockwool has different products for growers who might need to steer their crops towards more generative growth by having a drier root zone. It makes it much easier for the grower to then restrict irrigation and moisture levels in the root zone to steer the plants towards more generative growth and generally the technique is very effective. However, commercial growers use high tech tools likes moisture meters linked to their computerized irrigation program so that the crop is not at risk of being damaged by delaying irrigation to long. Smaller growers can certainly use similar techniques and allow the rockwool to run a little drier between irrigations and keep their nutrient run off to an absolute minimum if their plants are getting a bit too vegetative. Running a lot of nutrient through the rockwool on a frequent basis means the slabs or media are at saturation for much longer, and that favours vegetative growth (although we should also remember a lot of other factors, such as the growing environment, play in a role in the vegetative/generative balance as well).

Dr Lynette Morgan holds a B.Hort.Tech(Hons) degree and a PhD in hydroponic greenhouse production from Massey University in New Zealand. Her PhD thesis focused on hydroponic tomato production in both NFT and media systems and improvement of fruit quality aspects. Now a partner in SUNTEC International Hydroponic Consultants, Lynette is involved in many aspects of hydroponic production, including remote and on-site consultancy services for new and existing commercial greenhouse growers worldwide as well as research trials and product development for manufacturers of hydroponic products. Lynette is also the author of 5 hydroponic technical books: Hydroponic Lettuce Production, Hydroponic Capsicum Production, Fresh Culinary Herb Production, Hydroponic Strawberry Production and her latest release, Hydroponic Tomato Crop Production.

Over in Europe, NFT has been the preferred hydroponic method among hobby growers for many years. Now finally, it seems, the word is beginning to spread to hobby growers over on this side of the Atlantic. But what’s the real deal with NFT? Does it truly offer all these promised benefits to hobby growers without any catches or compromises? Is it just suitable for salad crops or can it deliver when applied to heavy, fruit-laden annuals like tomatoes and cucumbers?

Our main man with a high yielding plan, Everest Fernandez, takes a first look at NFT Gro-Tanks and shares some of his hands-on experience.

WORDS: Everest Fernandez

NFT 101

Ok, don’t be shy. Raise your hand if you don’t know what the hell NFT is. No worries! We’ve all been there, and that’s what I’m here for I guess …

NFT stands for Nutrient Film Technique. It refers to a general method of growing plants hydroponically. In NFT nutrients are added to water just like any other hydroponics system and this solution is contained in a tank. Plants sit on a grow tray above the tank and the nutrient solution is pumped up to the tray. The tray is positioned so that it lies on a slight gradient. The nutrient solution flows constantly over the roots feeding them all the nutrients and water they need. Any nutrient solution that is not up taken simply flows back through a hole into the tank where it is re-circulated.

But What Are The Plants Growing In?

The roots of your plants are constantly bathed in an oxygen-rich nutrient solution. It forms a thin ‘film’ about 0.03 to 0.1 inches in depth. A thin layer of capillary matting called “spreader mat” is first placed over the tray. This helps to spread the flow of the nutrient solution evenly over the entire surface of the grow tray. We all know that roots hate light. That’s why they tend to stay under the ground in nature! Fortunately the root zone is protected with a piece of Correx (kind of like a cross between cardboard and plastic). Small holes are cut into the Correx, just big enough for the base of the plants to fit through. This also helps to prevent algae growth in the root zone or nutrient solution.

Cucumbers grown in an NFT system.

The thin nutrient film not only provides your plants with all the water and nutrients they need, it also gives them access to loads of oxygen – essential to maintain key metabolic processes in the root zone that regulate how efficiently your plants can feed. This is a key feature of NFT. There are always some parts of the root zone that have more access to oxygen than others – simply because they are higher up: these parts of the root zone help to supply lower parts with all the oxygen they require. This is just one aspect of plant physiology that NFT growers exploit to their advantage. When plants have access to all this water, nutrient and oxygen simultaneously the growth rates can verge on being scary.

Gro-Tanks vs. Gullies

NFT Gro-Tanks can accommodate a far wider root system than the NFT ‘gullies’ you may have seen on commercial hydroponic farms (commonly used to grow basil and other leafy greens) making them ideal for plants that produce abundant root systems such as tomatoes.

Go With The Flow

NFT Gro-Tanks often come supplied as a complete kit for hobbyists – including the right sized pump. Solution flow is generally unimportant but should normally be between 1 to 3 pints (400 ml and 1500ml) per min. Channels should be sufficiently sloped, normally not less than 1:50 but may be much steeper if set-up allows, so that there is no “pooling” in the channels.

Plant Stability

What about heavy, fruit-bearing plants like tomatoes? Surely without any growth media, the plants are simply going to keel over due to their own weight, right? Amazingly, the plants form such a thick mat of roots underneath the Correx that they are very well supported. That’s not to say that some top heavy varieties won’t benefit from some net supports – but that’s often the case across the board when you grow plants near to their maximum capacity!

Propagation

NFT growers start their seedlings and cuttings off in the regular way, perhaps propagating in rockwool cubes or another inert media (e.g. net pot with clay balls.) Aeroponic cloning machines can also be used. Just as with any other hydroponics system, it’s really important to ensure that your seedlings or cuttings have a sufficiently developed root zone before transplanting them into an NFT grow tank. Don’t just wait for one or two roots to poke out. Aim for a mass of roots first! A great tip is to use an air-pruning tray (see UGM005, page 28) to generate a compact, dense root zone that’s bursting to break free!

Everest’s NFT Grow-Tank Tips

Here are some of my special tips learned the hard way:

1) If you are using rockwool starter cubes, ensure that the ridges at the bottom of the cube are in line with the nutrient flow, not perpendicular to it. Otherwise your nutrient flow will be impeded.

2) No growth media around the root zone means less insulation and less protection from extremes in temperature – so you need to have your garden’s environment dialed in. The temperature of your nutrient solution is also crucial – but this is no different than with other hydroponic applications. Try to keep your nutrient solution at around 65°F for high levels of dissolved oxygen and optimum nutrient uptake.

3) Plants grown indoors under lights will take up water at a greater rate than they take up nutrient. Over time the EC (CF) of the solution will rise. Regularly top up your tanks with water or 50% strength nutrient solution. Keep your top up nutrient solution in a separate barrel rather than using water straight from the tap.

4) Maintain the pH of your nutrient solution at around 5.8 – check regularly as it can rise as the plants feed.

5) As a general rule, drain your nutrient solution and replace with a fresh batch every 7 to 10 days for optimum yields. Obviously bigger tanks can get away with less frequent changes whereas bigger plants prefer more regular fresh nutrients. For more information on nutrient change-outs make sure you read ‘Maximizing The Nutrient Environment’ by Lawrence Brooke (UGM004,005,and 006).

6) Do not let any light leak into the root zone. Ensure the holes in the Correx cover are just big enough for your plants to fit through. Cover the bases of your plants to prevent green algae forming – especially important if using rockwool cubes.

7) Thoroughly clean your tanks in between crops with a soap solution and rinse thoroughly.

Wait until roots are showing out of your starter blocks before inserting them into your NFT system. This is absolutely crucial!

9) Use a half strength nutrient solution to start your plants off, moving to two thirds to full dosage rate (as detailed on the bottle) after the first nutrient solution change (about 7 – 10 days after planting).

10) Take the opportunity to observe your plants’ root growth directly by simply lifting up the Correx cover!

11) Make sure you completely remove plastic wrapping from rockwool cubes or remove pots if using soil or coco. This allows the roots to access more oxygen.

12) NFT is a bare rooted growing technique. All but the smallest of plants will need additional support, i.e. yoyo’s or pea netting.

13) Cut lengths of spreader mat long enough to allow an overhang of a few inches from the channel into the tank. No trickling water sounds!

14) Don’t crowd them! Plants grow incredibly fast in NFT Gro-Tanks – many growers are overwhelmed!

Think NFT – Think Sushi!

NFT constantly provides plants with the opportunity to feed rather than other methods which just provide several opportunities to feed. It’s a bit like sitting in one of those once-trendy sushi conveyor belt restaurants all day, every day. You, like your NFT plants, can take what they want, when they want it, rather than having to wait for their next feed. As a result, you and your plants are going to end up very happy and heavy!

Planting out and Irrigation

First, mark your planting sites with a marker on the Correx sheet. Do not position any plant too close to the pump. Make the holes just big enough. The aim of the game is to allow your cuttings or seedling access to the nutrient film without letting light in through gaps. Lay a single layer of spreader mat over the grow tray. Run your pump 24/7, day and night. There’s no need to work out irrigation cycles and frequencies. Your plants will simply absorb as much or as little nutrient as they require. This is perhaps one of the most appealing aspects of NFT. You should be able to see obvious root activity within 24 hours of planting out. Root axes grow into the nutrient film. Fine root hairs will also grow around the propagation media.

Incredible Root Development

One of the best aspects of NFT growing is the ability to peer at the huge mat of roots that quickly develops underneath the Correx cover. It’s easy to assess the health of your plants – just look for a thick mat of white roots! Watch that the roots don’t get carried away and grow into the pump. (Unlikely, but it does happen.) Clean-up in between harvests is a lot less hassle than with media-based growing methods too, mainly because there is so little media to deal with. This makes NFT Gro-Tanks a great choice for the hobby grower who doesn’t want to endure the regular hassle, expense (and back ache!) of carrying endless bags of soil, coco or clay pebbles.

The Verdict?

Once I tried NFT I immediately saw the benefits, despite grossly overcrowding my Gro-Tanks with waaaay too many plants on my first few attempts. You live and learn. Since then I have come to appreciate that less is, indeed, more!

A greenhouse full of plants grown NFT-style.

Oyster mushrooms are a large, diverse and colorful group of mushrooms. They are found all over the world and can range in color from white and grey right through to blue, yellow and even bright pink!

Commercial cultivation in bags of straw hung from the ceiling.

Oysters are the easiest mushrooms to grow and can use a wide range of agricultural wastes as food – from straw and woodchips to sugarcane and coffee. I know of one coffee distributor in Great Britain who collects used coffee grounds from the restaurants he supplies and then uses it to produce many pounds of mushrooms per day. You can even grow them on books, phone directories and toilet rolls.

Oyster mushrooms are a good place to start if you are interested in growing your own as the raw materials are cheap and the mycelia grow so quickly that contamination has little time to take hold. Yields are among the best of all cultivated fungi.

A few of the most interesting oyster mushrooms are discussed below.

Tree Oyster or Blue Oyster (Pleurotus ostreatus)

Young blue oyster mushrooms.

This is the classic oyster that has long been a favorite with mushroom hunters for years! Wild specimens have been found weighing 44 lbs (20 kg) and nearly 10 feet (three meters) in circumference! They are easy to grow on straw and are prolific producers. Many cultivated mushrooms suffer from pests called nematodes, which are like small worms that can feed off and damage the mushroom mycelium. No such problem for P.ostreatus – it has been shown to secrete a metabolite that stuns the nematode. The mushroom mycelium then invades the helpless nematode and quickly consumes its internal organs. That’s a mean mushroom!

The Golden Oyster (Pleurotus citrinopileatus)

One of the most spectacular of all fungi – with clusters of bright yellow to golden caps. It can have quite a bitter taste when fresh and is best when thoroughly cooked.

Golden Oyster mushrooms.

The Pink Oyster (Pleurotus djamor)

Probably the fastest growing of them all, this tropical species produces brilliant pink fruits. Not regarded as the best tasting of the group, it does however have a place, especially in developing countries as it can be grown without the need for much equipment.

Pink Oyster mushrooms.

The King Oyster mushroom

This is the oyster mushroom with the best flavor. Much more commonly seen in markets in Europe, it can be collected from the wild or grown on tree stumps or straw outdoors or indoors. It has thick solid stems and keeps very well after harvest.

Commercial cultivation of King Oyster mushrooms in bags.

The King Tuber Oyster mushroom (Pleurotus tuberregium)

This is an unusual species that forms a large tuber called a sclerotia or “truffle” (which looks a bit like a kind of large alien egg). These “eggs” can then be planted in sand and large mushrooms sprout directly from them.

Cultivation

All of the species above can be done at home using a similar method. Initially the mushroom is grown on grain that is then used to inoculate straw or a similar substrate, which has been heated in a hot water bath (“pasteurized”) and allowed to cool. The straw is loosely packed into bags and rapidly becomes covered in mushroom mycelium. Holes are then punched into the bags and mushrooms appear in abundance! You will be astounded at the amount of fungi you can produce – so give it a go!

Inspired to have some fungi? Still got some questions you need answering? Join the discussion and post your thoughts below!

The Latin word “Fragaria” reveals further insights into the fruit: the word means “fragrant” – an apt, if incomplete, description of this fabulous, even erotic fruit. Serving the object of your affection strawberries and champagne is known as a sure way to heat up a private and intimate evening (add chocolate to induce flaming). Even the indigenous Americans realized the amorous and lusty qualities of the strawberry. All you need to do is check out some sacred Cherokee texts: the credit for strawberry creation was the forthright thinking of the Great Apportioner, or The Sun. The Cherokee teach that strawberries were made to melt the first woman’s hardened heart and repair her relationship with the first man after a quarrel. Obviously, The Sun is a very wise dude for a deity.

STRAWBERRY FAST FACTS

• pH range 5.5-5.8 for best results
• strawberries like low humidity
• 65-72 degrees F / 18-22 degrees C best for fruiting
• 14 hours of daylight minimum
• crop yield: up to 3lbs fruit per plant
• grow 60lbs berries in 1.36 square feet
• harvest 12 months/year is possible

Things were a bit different in Europe, where the earliest record of strawberries is found in 200 BC Rome. Originally, they only had medicinal uses. A 12th century saint deemed the berry to be unfit to eat, claiming they were contaminated by toads and snakes as they grew on the ground. France began cultivating strawberries in the early 1500s when Cartier brought plants back from Quebec. King Louis XIV declared them his favorite fruit, launching a poetry contest for the purpose of composing rhyme on its many wonders.

No improvements to strawberries were attempted until the 18th century. Before then, strawberries were all the small-yet-tasty little morsels you still find growing wild. The first U.S. hybrid, “Hudson,” was introduced in 1783. However, it was the English who became scientific and systematic about the hybridizing of the strawberry in the 1820s. To them we owe thanks for the huge, beautiful berries we so enjoy today. The first cold shipment of commercial strawberries took place in Ohio of 1843. This colossal concept evolved in Cincinnati when some ingenious berry farmers had the brainstorm of making ice on box tops to refrigerate their perishable cargo in transit.

Alas, the impressive looking berries you buy in the grocery store aren’t chosen for flavor, but appearance. After all, the majority of us are suckers for looks and few care for what lies beneath the skin. Commercial strawberry varieties like Chandler, Camarosa and Sweet Charlie contain about half the sugar as the luscious garden types our eyes perceive them to be. Retail berries are selected for long storage and huge fruits born in much abundance. They lack sweetness, juice, and are devoid of that hauntingly beautiful strawberry fragrance and flavor.

The amount of chemicals used in the commercial production of strawberries is phenomenal. We can sympathize with soft fruit producers and their plight as they attempt to earn a dependable living with this perishable crop against the odds of Mother Nature, but the alarming use of methyl bromide and chloropicrin is only the tip of the chemical iceberg when it comes to the methods employed to bring globe-trotting strawberries to your local food market. And if you thought that the soil fumigant methyl bromide was completely put to rest, it isn’t. The EPA has extended the window until 2012 to allow for a replacement chemical to be produced. Methyl bromide is toxic to the ozone, causes lung cancer when breathed and does not wash off of the berries as it is absorbed by the skin.

So what’s a conscientious strawberry- lover to do? Simple! GROW YOUR OWN!

Hydro heads will also be delighted to know that strawberries love hydroponics and you can harvest mouthwatering fruit all year long. Hydroponic strawberries are far juicier with richer flavor than soil-grown crops outdoors. You can harvest your own huge “Junebearing” strawberries all year. Fresh strawberries consistently ready to pick? About now you’re poised on the edge of your seat waiting to know more, right?

Recommended Hydroponic Strawberry Varieties

Different regions of the USA and Canada grow strawberry cultivars that perform best in their specific climate. For indoor gardeners, of course, climate isn’t an issue and you can pick the variety with all your favorite attributes. If you want to keep your energy costs down then pick day-neutral types that do best in short days and cooler temperatures.

Strawberry varieties aren’t as simple to select as you may think. There are three distinct bearing types to consider: June-bearing, ever-bearing, and day neutral. June-bearing puts all its energy into creating massive, juicy berries once a year, spreading via runners up to 3-feet wide. Ever-bearing plants yield three crops a year in soil with resting periods between fruiting, even in your indoor garden.

Day neutral strawberries will continually produce fruit once they reach the bloom stage. Day neutral berries are smaller than the other types but have excellent flavor and sweetness. Day neutral berries will deliver the biggest bang for your buck when growing indoors. The queen of hydro strawberry production, Dr. Lynette Morgan, agrees and adds this is the best choice for consistent day lengths. These will perform well in shorter day lengths and cooler temperatures for lower production costs.

Don’t assume that such a crop will take over your grow space for a good sized harvest. Strawberries are great for growing in hydroponic stackers that only need 14 square inches of floor space to grow 20 plants. However, make sure you check the disease resistance of varieties and the known yield amounts. There are some excellent choices in all three types of strawberry plants.

Day Neutral Strawberry Varieties

Tribute: fruits spring through fall; medium to large berries.
Quinalt: self-pollinating; 2” wide berries with 4-5 month harvest.
Mara de bois: productive; firm, good-sized fruit with outstanding flavor.
Seascape: popular; firm, good-sized fruit with nice flavor.

June-bearing Strawberry Varieties

Honeoye: heavy yields of gorgeous big berries excellent for freezing.
Jewel: huge berries with exquisite flavor high in sugar content.
Earliglow: fast to flower and fruit; great flavor, size, color and juiciness.

Ever-bearing Strawberry Varieties

Ozark Beauty: prolific harvest of very juicy berries with good flavor.
Ft. Laramie: a bit smaller fruit with good harvest and superior taste.

Nutrition Facts

Here’s an interesting tidbit: the actual fruit of the strawberry plant is what we call the seeds. The ambrosia we so adore is more like a fruit-carrying pod. This pod from the gods needs no description of flavor or what makes the crop so special. After all, you may (in the course of a century) meet up with two or three souls who detest strawberries.

Strawberries offer us a mountain of health benefits. Ten medium sized berries contain 150% of your daily Vitamin C requirements: the equivalent of a whole orange. They also contain Vitamin K, B2, B5, B6 and are rich in iron. Strawberries are fat free and the same serving contains 3g of carbohydrates, 2g of protein and 7% of your daily folic acid needs. The seeds of strawberries contain natural whitening agents for your teeth and are wonderful for removing dental plaque.

Strawberries have held medicinal value since the days of Rome. They are excellent antioxidants that control free radicals and combat carcinogens. Unlike many other fruits and vegetables, cooking does not destroy these qualities. They are also a good source of flavonoids and have excellent antibacterial properties. The seeds most of us wished weren’t present are a great source of dietary fiber and assist in reducing cholesterol.

What Do I Need to Grow Hydroponic Strawberries?

Now, before you rush off to Google the best price on strawberry seeds, I feel I should inform you that you’ll be hard pressed to find any select cultivars available. In fact, you’ll most likely not find any proper strawberry seed at all to purchase. You can grow strawberries from seed, but who wants to wait 2 to 3 years before picking their first berries?

The best-yielding strawberry starter plants are newly-rooted runner cuttings called “plugs.” These will be available in spring mail order catalogs everywhere. Buying live strawberry plants bare root is not a wise choice for hydroponics. The soil-borne pathogens in field-dug bare root strawberry plants available in the fall could be your worst indoor gardening nightmare when those pathogens run wild in a recirculating system.

Strawberry plugs are simply rooted runners. Once you’ve got your first plants going, you’ll have plenty of runners to grow your own plugs. Elongated daughters give higher yielding plants than runner tips. Once rooted, 6-12 weeks of refrigeration results in growth to flowering in a few short weeks. The larger your plug pot size, the higher performance your new plants will have.

The least preferable system for strawberries is NFT as keeping crowns raised becomes an issue and rockwool can cause over-saturation-related root problems. Media-based systems are far easier to maintain good strawberry disease control. A Spanish study proved that the highest harvest yields and fruit weight were found to be using sphagnum peat and not coir for the substrate. You must have excellent drainage and take care to keep three quarters of the crowns raised for air flow to preempt root rot and foliar diseases. So clay pebbles, vermiculite, gravel or perlite may be best for beginners to achieve best results.

Strawberry plant crop yields vary from about one half pound to three pounds per season. Since hydroponically- grown plants have heavier yields, a June variety known for abundance could easily yield three pounds per crop. Stackers of 20 plants could yield 60 pounds per harvest in just 1.36 square feet of area. Dr. Morgan suggests that elevated systems are preferable to the floor, as it improves airflow. Your grow lights should be metal halide or full spectrum fluorescents. With day neutral varieties you can have a great harvest with under 12-hour day lengths. You’ll want good air flow and venting to keep the humidity down for a more carefree crop. Your water can’t have high sodium as strawberries are intolerant of it, so under 50 ppm sodium is best. If you live in an area where these values cannot be met, a water purification filter could be the answer for you.

You want to maintain a pH range of 5.5-5.8. For best performance, strawberries like low humidity, a minimum of 14 hours of daylight and warmer temperatures. Day neutral varieties have been known to fruit well at as cool as 60˚F (16˚C), but temperatures between 65-72˚F (18-22˚C) are best for strawberry fruiting. Good air flow is needed for plant vigor with strawberries, which are prone to powdery mildew in high humidity.

Good crop management will include keeping any older, browned or discolored leaves and overripe berries cleaned out regularly. Their presence creates good breeding grounds for problematic pests and disease.

Strawberry Harvesting Tips

Once you get your berry crop well under way and practice good crop management, you should be enjoying fresh berries just about any time of the year. The new plants should begin flowering in 8 to 10 weeks with your first fresh, safely grown strawberries ripening not long after.

Learning the ultimate point at which to pick your berries will be a bit trial and error at first. Berries will not generally ripen after being picked so it is best to harvest your strawberries as they reach the point of perfect ripeness and place them in refrigeration (if not in your mouth!) as soon as possible after picking. This will inhibit the soft fruit from reaching a point of over-ripeness too quickly.

Unlike berry harvests from soil-grown plants, hydroponic strawberries won’t be covered with dirt. You’ll be able to eat them fresh just as they are plucked from the stem. This will reduce the need to introduce your ripe fruit to water that can rush spoilage even in cold storage.

Strawberry Freezing Tip

Cut the green plant tops off the strawberries and spread the berries in a single layer on a baking sheet. Freeze the berries for 1-2 hours, then move them to Ziplock bags for permanent freezer storage. This will ensure your berries don’t freeze in a solid mass, making it easier to remove and thaw as many berries as you need at a time.

Do you have a favorite strawberry variety or growing method? Tell us about it below!