One thing’s for sure: a big decision that divides growers is their choice of base nutrients – the type, as well as the brand. We often receive emails from growers asking us if two-part nutrients are better than one-parts, for instance, or if a three-part nutrient is the gold standard. So we decided to hook up with Simon Spinks and Callie Fixter, biological scientists from British nutrient company VitaLink, to try and discover some homegrown truths and perhaps dispel some myths along the way …

Everest – Hi Callie, Simon – thanks for dropping into Urban Garden HQ! Now, I know you guys are probably keen to wax lyrical about how marvelous your nutrients are, but can we start by addressing a certain ‘prejudice’ that some growers have towards one-part nutrients? Can you, as people who know their nutes, tell me straight: are one-part nutrients designed for numpties?

Callie – (laughs) Numpties!?

Everest – Novice growers.

Callie – Oh no. Not at all.

Everest – Really?

Callie – No, but I can’t say I haven’t heard it before. And not just from growers either. A lot of retailers also believe this. In fact, we’ve heard of several retailers advising their customers that a two-part nutrient is preferable to a one-part. Then I guess that customer passes this advice on to their friend and so forth, leading to the reputation that a one-part nutrient does not deliver the goods like a two-part.

Everest – So what do you say to growers who claim that one-part nutrients are “weaker” in some way?

Callie – Well … admittedly there were some one-part nutrients available in the 1990s that didn’t deliver very good results – perhaps that’s why the two-parts took off like they did. It used to be very difficult to stop individual nutrients and elements within a one-part nutrient from reacting with each other in the bottle. This reaction is detrimental to plant growth because it effectively causes nutrient lock-out, meaning plants don’t get all of the nutrients and elements they need. Two-part nutrients separate the calcium from the phosphates and sulphates by putting them in different containers (i.e. A+B). This avoids the chemical reaction and prevents a precipitate or solid from forming at the bottom of the bottle.

A Menu for Healthy Plant Growth

A Good Nutrient Provides:

• All of the nutrients and elements your plants require.
• Nutrients and elements in the right amounts.
• Nutrients that your plants can readily absorb.

Simon – A lot. Technology and nutrient manufacturing has moved on considerably. Today, one-part nutrients are made very differently than two and three-part nutrients. As a result, VitaLink, along with a number of other respectable nutrient manufacturers, offers, growers a one-part nutrient that takes the fuss out of mixing, whilst still offering great plant results.

Everest – Ok, but what exactly is different?

Simon – Well, that depends on who you talk to, Everest. There are a number of ways one-part nutrients can be made. One method that we use is called ‘Suspension Technology.’ A ‘suspension’ usually refers to a solid within a liquid. In the case of the VitaLink one-part nutrients ‘Easy’ and ‘Coir,’ the ‘suspension’ is a mixture of various minerals and a very important biological ingredient. The biological ingredient acts like a cage, absorbing a large proportion of the calcium to prevent it from reacting with the other nutrients. As well as preventing these nutrients from reacting with each other, this biological ingredient also helps your plants to absorb a maximum amount of nutrient, promoting fast, healthy growth. This way of making a one-part nutrient means that when the bottle is shaken (it’s vital to shake a one-part nutrient), you can add one blended dose of nutrients and elements in a form that your plants can easily absorb.

Most growers also don’t know that the way we formulate our one-part nutrients actually helps with the pH stability when they start feeding it to their plants. This is because the biological ingredient present actually helps to buffer the pH. This buffering effect prevents the pH of the nutrient from changing too rapidly. This means that the maintenance of your nutrient tank is a lot easier because the need for pH Up and Down is reduced.

Everest – Fair enough. So you’ve developed some biological “jizz” to keep everything fine and dandy. But isn’t it just better to go for a two or a three-part nutrient if you know what you’re doing?

Callie – No, not necessarily. It’s a common misconception: ‘more parts equals more yield.’ But I don’t think this is true. A three-part nutrient definitely offers you more control over what you are feeding your plants. It allows you to ‘tweak’ the NPK ratio throughout the growth cycle, enabling you to respond to any signals that your plants are giving. Three-part nutrient manufacturers provide usage directions, which I would recommend following. But the added complexity from the feed schedule of a three-part nutrient also makes it easier to make a mistake, so use with care.

Everest – But aren’t we back to where we began? Three-part nutrients are more complex to use … meaning one-part nutrients are simpler, i.e. they are designed for beginners!

Callie – No, one-part nutes are designed for growers who want to make life easier for themselves!

Everest – Yeah but no but yeah but no but WHICH IS THE BEST? One or two-part?

Simon – Look Everest … without meaning to sound like we’re sitting on the fence, it basically comes down to choice, which is why we developed both one and two-part nutrients. We knew there was a market for both, so we made both. Our newer one-part nutrients are increasingly popular with novice growers, but are also great for any grower looking for low-maintenance growing. At the same time, our two-part nutrient, VitaLink ‘Max,’ has enjoyed great popularity in the UK and throughout Europe too.

Everest – Okay, I’m hearing you. Thanks for coming in to say hello. How about we do a side-by-side trial of your one and two-part nutrients one of these days?

Simon – Sounds good to me!

Nutrient Types: Advantages, Disadvantages and Tips

One-part
Ideal for new growers or those looking for the simplest growing. Easy to use, low-maintenance. The bottle needs to be shaken to ensure a complete dose of all nutrients. Shake the bottle and simply pour until you reach your target nutrient strength/conductivity.

Two-part
A great choice for all abilities. Many growers using a one-part nutrient go onto a two-part nutrient for experimentation. Extremely popular, gives more control over the mixing process than a one-part nutrient. More risk of mixing errors than with a one-part nutrient. Always adjust the pH after you add your nutrients.

Three-part
Maximum control over mixing process. Mixing errors are more likely. Always follow the feed schedule supplied with the nutrients.

What’s your opinion on one part vs. two part vs. three part nutrients? Tell us where your allegiance lies!

For more information on VitaLink, please contact the following distributors:

Hydrogarden www.hydrogarden.com
Nutriculture www.nutriculture.com
Maxigrow www.maxigrow.com

The glorious coconut has been providing us with much more than the odd Piña Colada for centuries. Traditionally, coconut coir (the outer fibrous husk) has been the backbone of “Welcome” doormats, brushes, sofa stuffing and horticulture for well over 100 years but, as far as hydroponics is concerned, coco coir started to make a name for itself during the late ’80s and early ’90s as a substitute for peat and rockwool, both non-renewable resources. In a nutshell (sorry, couldn’t resist), coconut coir is an environmental by-product of the long-established coconut industry. It’s a 100% renewable resource and the environmentally friendly alternative to bog dredged peat moss.

So what is it about coco coir that makes it such a popular replacement for peat and as a hydroponic medium in its own right? Firstly, check out its outstanding water and air holding capacity. Unbelievably, coco coir can hold eight to nine times its own weight in water! More importantly, coco coir holds a lot of air, in fact even when saturated it typically still holds around 22% air. In this respect it is superior even to rockwool, the world’s most popular hydroponics medium. Rockwool is a great medium but some beginners can easily run into trouble as it typically only holds around 10% air, leaving plant roots in danger of becoming oxygen deprived, particularly when the nutrient solution temperature is over 68-72°F (20-22°C). (The warmer a nutrient solution is, the less dissolved oxygen it can hold.) With coco coir, however, this type of overwatering (or, to put it more precisely, oxygen deficiency in the root zone) is avoided by the enormous amount of air that good quality coco coir can hold.

The amazing properties of coco coir don’t end with excellent water and porosity. Oh no! The best aspects of coco coir are far more varied! Did you know that coco coir possesses antifungal and root promoting properties? As coconuts spend long periods of time floating in the sea before they beach themselves and sprout a lovely new coconut tree, their physical dynamics have to be incredibly tough and unique to survive such a harsh, salty environment and still be able to sprout and grow when the time arises. These properties are available for you, the indoor gardening aficionado, to freely exploit in your quest for your perfect indoor garden. Recent studies have shown that coco coir has a great ability to suppress and protect plants from phythium and phytophthora, two very unpleasant root diseases that can quickly ruin your crop and put a real dampener on your day, week or month! This is very helpful if you are using organic-based nutrients, as these can contain high levels of urea that can build up and burn your plants.

Qualities of Coco Coir

• Coco has ideal pH in the range of 6-6.7
• It holds 8 to 9 times its weight in water
• It holds 22% air even when fully saturated!
• It has excellent drainage and air porosity for better plant growth
• The top layer always remains dry, leaving behind no chances of fungal growth
• It never shrinks, cracks or produces crust
• It aids in suppressing fungus gnats, to a degree
• Excellent cation exchange
• Its anti-fungal properties help plants to get rid of soil borne diseases (inhibits pathogens like phythium and phytophthora)
• Extremely easy to re-hydrate after being dehydrated
• It is a 100% renewable resource
• Lightweight
• Completely environmentally friendly

So what makes good quality coir?

There are three parts to a good coco medium: coco fiber, coco pith (coco peat), and chips. Each part brings its own attributes to the table.

Coco Pith

Coco pith / coco peat holds a large amount of water but is smaller and facilitates much less capacity to hold air. It is more lignin (woody) and decomposes very slowly. Properly aged, it contains the complex that holds potassium and sodium until it is fertilized and a stronger ion, usually calcium, bumps these off, thereby locking up the calcium and freeing large amounts of harmful salts. Proper aging of this coco pith is critical. It affects the crop time since a minimum amount of time is required to make this usable, at least four months, which reduces the amount of time available for use.

Coco Fiber

Fiber holds little water but increases the capacity to hold air; the more fiber you see in your coco mix, the more often you will need to water it. Fiber is largely cellulose and degrades fairly quickly. This degradation has an adverse affect on the stability of the medium. The length of these fibers is also critical to these functions as well.

Coco Chips

Coco chips combine the properties of the fiber and pith; they are approximately the same size as the fiber and positively influence air-holding properties while holding water. Chips hold less water than pith or fibers. They have the highest air to water ratio of all three parts. Achieving the correct ratio of these components is critical in developing a well-drained, well structured medium for growth, just as the proper preparation of the chemical characteristics is important by buffering the blend before use. (Hydroponic-grade coco coir growing medium has been treated so that unwanted potassium and sodium has been removed. This helps to ensure that the nutrients you later add to the coco coir can actually be used by your plants.)

Storage and Sterilization

Coco is usually stored in giant piles for a couple of years at its country of origin. Unless stored carefully, these huge coco piles can be susceptible to colonization by unwanted pathogens (partly due to the pH of the coco being favorable to pathogens) so, in this case, the coco must be steam or chemically sterilized in order to make it suitable for horticultural use. However, chemical sterilization can have adverse effects; and steaming destroys the structure of the coco peat while converting any nitrogen present into a toxic form, nitrite nitrogen; both destroy any beneficial organisms that are usually present. So what’s the solution? A coco coir supplier needs to control the coconut from harvest to bagging, remove the opportunities for unwanted seed and pathogen contamination, and carefully control the aging process directly. Only then will they stand a chance of producing the cleanest, most alive and most productive form of coco coir. Regulations vary between countries with regard to sterilization (Australia is very strict). Shipping microbes across continents is frowned upon by customs agencies. Some brands are inoculated with specific microbes that are either allowed to cross borders or are blended after landing on the shores where they ultimately will be used.

Finally, caring for the product through proper storage and packaging is critical, after preparation and again after packaging. Storing it too wet speeds decomposition. Drying in big mechanical driers can also have a detrimental effect on structure. In short, improper handling will drastically reduce the ability of the product to provide the correct root environment for proper root growth. Finally, consistency: a grower needs to be sure that they are growing in the same material crop after crop to ensure success. Imagine the heartache of losing a crop because the salts were not properly washed off your latest batch, or the coco peat is too decomposed – this REALLY happens!

So don’t be afraid to ask questions of your coco supplier. Look for an established supplier that sun dries the coco, one that incorporates the correct coco pith, coco fiber and coco chip fractions to get the best blend. This is specific to the grower’s irrigation system, the plants being grown, and the size of the pots used. For instance, you wouldn’t grow orchids in fine coco pith as they require lot of air! Conversely, any fast growing vegetable in warm conditions would enjoy lots of coco pith in the mix. Look for coco that is clean and washed correctly, one that is packaged and stored correctly, and one that is correctly aged.

Preparation

Let’s take a look at how this natural product should be prepared by the manufacturer. This is the biggest concern in selecting coco coir for hydroponics use. The outer fibers of the coconut are removed by soaking them in water. This soaking process involves either the use of fresh water or, more commonly, the use of tidal water which can be very high in salt. As coco coir has an excellent cation exchange ability it tends to hold onto things like salt which, when used in a hydroponic or indoor set up, can wreak havoc on your plants. Good quality, hydroponic grade coco coir will have not have a high salt content, but you should always flush it through with a low EC nutrient solution before use until no more tannins are coming out. Tannins can easily be seen as they stain or color the water brown. Some indoor gardeners check to see if the PPM of the water coming out of the coco is the same as the water they’re putting in – but a more reliable method is the 1:1.5 extraction method which better determines the actual pH and EC of the coco itself.

The 1:1.5 Extraction Method

A reliable method for measuring the nutrient levels in coco coir is using the 1: 1.5 extraction method. EC and pH of the root environment can be determined by using this method. The pH and EC of the drain water generally deviates from the actual root situation, as coco coir is able to retain and release elements.

1) Take a sample of coco. This can be done with a soil core sampler or a trowel. To get a representative sample the coco must be collected from as many places as possible.
2) Collect the sample in a bowl and determine whether it contains the right amount of moisture. The coco has the right amount of moisture if moisture disappears between your fingers when you squeeze it. Add de-mineralized water if necessary and mix the coco.
3) Take a ½ pint (250 ml) measuring jug and fill it with just over 4 fluid ounces (150 ml) of de-mineralized water. Add coco to the ½ pint (250 ml) mark.
3). Fully mix and allow the slurry to settle for at least two hours.
4) Mix again and measure the pH.
5) Filter this material out and measure the EC of the water remaining.

The target values for EC are between 1.1 and 1.3 (of course, lower is acceptable too!).
Target values for pH are between 5.3 and 6.2.

Reproduced with permission. Copyright CANNA.

The best way to irrigate coco coir in pots is via drippers. This is the best way to ensure that the growth media remains consistently moist (but not overly wet).

Coco-specific Nutrients

There are a number of manufacturers out there who offer a ‘coco specific’ nutrient formula. These specific formulations are based on the tendency of coco coir to hold onto phosphorus, while only holding a little calcium, while giving off small amounts of potassium. The best nutrient formulations for coco coir will therefore have some extra calcium, but not too much as it will compete for potassium uptake resulting in a potential for potassium deficiency. So are they any better? Well, generally speaking any good, complete hydroponic nutrient is more than suitable for coco coir as these invariably contain all the calcium needed to provide for excellent growth in coco coir. However, for best results, a purpose-made nutrient is best. When feeding nutrients to plants grown in coco coir, aim for a pH of around 6.0 as this will allow maximum availability of all nutrient elements. Remember, a slightly fluctuating pH is a good thing (say between 5.5 and 6.5) as it opens the doors to different nutrients. As for feeding times and frequency, that is really going to depend on what type of system you are running; but for those replacing their peat mix or rockwool with coir there is essentially nothing you need do differently, as far as feeding frequency, flushing, et cetera goes.

So there we have it. Coco coir is an amazing and renewable medium that is ‘top class’ for both performance and benefits. So go on and try this amazing medium, you’ll be glad you did.

CONTRIBUTORS:
Geary Coogler, B. Sci. Horticulture, HORTISOL North American Research
Adam Hanscom, General Hydroponics

WORDS: Everest Fernandez

Growing indoors is totally different from growing outdoors. Ok, so plants still need to be fed and watered so that they photosynthesize, grow and bloom, but there’s one important factor that’s fundamentally changed. The Sun! It may sound mind-numbingly obvious but it’s a fact that’s really worth exploring further: the biggest difference between growing indoors and outdoors is LIGHT.

We still need light, of course, and many indoor gardeners use grow lamps to produce it artificially. However, if you are growing plants that require high light levels (warm season vegetables such as cucumbers and tomatoes or exotic palms, herbs or cacti) are your grow lamps really going to cut the mustard? Granted, grow lamps are bright (very bright!) and, like the Sun, it’s a bad idea to stare at them! But we should really end the comparisons there. A 1,000W grow lamp compared to the Sun? Are you kidding me? Can you hear that? It’s God laughing. I mean, when you look at the stats, it’s not really a fair comparison. Can you imagine a grow lamp that’s over a million times the size of Earth? Hmmm … that’s beyond my visualization skills … but despite the huge physical differences between a regular grow lamp and the Sun, it’s still all too tempting to think of our grow lamps as direct replacements, hang them above our plants, and expect them to do exactly the same job.

SUN FACTS

• Pedantic scientists claim that the inside of the Sun is completely dark. It’s only the Sun’s outer surface that shines brightly.
• The surface of the sun is about 10,000° Fahrenheit (5,500° Celsius).
• Despite being dark, the center of the sun is a lot warmer than the surface: 27 million °F (15 million °C) (some might even say that’s a little on the hot side).
• Light from the Sun takes eight minutes to travel 93 million miles in order to reach us; it takes another half an hour to reach Jupiter and seven hours to reach the edge of the Solar System.
• Just like how planets orbit around the Sun, the Sun orbits around the center of the Milky Way galaxy, taking 225,000,000 years to complete a full orbit, traveling at 800,000 kilometers per hour. Hold on to your seats!
• The Sun weighs 1,989,000,000,000,000,000,000,000,000,000 kilograms! That’s about 4,384,994,390,000,000,000,000,000,000,000 pounds. Ahem, I think somebody indulged too many extra large fries…
• … not surprising then: the Sun is actually on a diet. Every time hydrogen nuclei fuse together to form helium nuclei, which results in a burst of energy, heating up and powering the Sun, it loses a tiny amount of its mass … about 4 million tons a second.
• … but despite decreasing in mass, the Sun will eventually increase in size to the point where it completely engulfs the Earth (and other inner planets) before collapsing into nothing … well nearly nothing … a very small “White Dwarf.” Sobering thoughts indeed.
• The Sun is nearly half-way through its life, and is running pretty well at the moment. However it is no longer under warranty and is due for its 5 billion year service pretty soon.

Consider the usual application and positioning of a High Intensity Discharge grow lamp. Usually it is placed overhead just a few feet above the top of the plants. A reflector is used to direct the light downwards. A really important fact to note is that some parts of the plant will be twice or three times the distance from the grow lamp as other parts. Have you stopped to consider how much less energy the lower parts of your plants are receiving than the tops? Remember, your grow lamps are nothing like the Sun. Outdoors, an extra few feet between the top and bottom of a plant is no big deal as far as the Sun is concerned… I mean, it’s already travelled 93 million miles to get here! I think the Sun can stretch to an extra few feet. But an extra few feet to your grow lamp is a different story. Relatively speaking, if we were twice the distance from the Sun, it would be like we were suddenly on a different planet – one reason why Martian summers are so crappy.

Grow Lamps and the Sweet Zone

So what’s the solution? Knowing how quickly the precious light from your humble grow lamps diminishes in strength, it would seem that the name of the game is to get your plants as close to your grow lamps as possible. But, of course, grow lamps radiate heat so they always need to be kept a safe distance away from your plants – otherwise you’ll end up with a lot of crispy dead leaves! If you place the back of your hand near to a grow lamp when it is switched on (being careful not to actually touch the grow lamp!) you can physically feel the heat it gives off. If you leave your hand there for a while it will soon start to feel uncomfortably warm. If any part of your plant resides in this zone it will most likely start to show signs of heat burn. The safe and comfortable distance from a grow lamp depends on wattage, plant variety, and other environmental factors. Ideally, you should invest in a light meter. If you don’t have one, then one approach is to use the back of your hand as a very approximate measure – you should not be able to feel a definite and gradually increasing warmth. Admittedly, this is far from a scientific approach, but at least it’s a real world rule of thumb that’s served me fine over the years. The closest point to the lamp that qualifies this test is roughly the optimum distance from the grow lamp. In other words: it’s as close as possible but not too close! This point is often referred to by experienced indoor gardeners as the “sweet zone” – so named because it is in this area that the most vigorous growth and bloom is often to be found. Trouble is … if you’re hanging your grow lamps above your plants at this safe distance, only the very tops of your plants enjoy it! Anything lower down gets exponentially less light.

Growers have devised a myriad of strategies to ensure that as much of the plant as possible basks in this “sweet zone.” Some growers bend, prune and train their plants indoors to form wider canopies (and thus increase the proportion of the plant in the ‘sweet zone’). Others take a far more radical approach and place grow lamps at the sides of their plants.

Supplemental Side Lighting

Supplemental side lighting is the technique of adding grow lamps in order to light the sides of the plants. Some growers use banks of T5 florescent tubes (which can be placed closer to plants than HID lamps). Other indoor gardeners use an additional HID grow lamp positioned adjacent to the plants at 90 degrees to the lamp above. The result is increased fruit and flower development across the entire height of the plant. When adding lights in this way, you may well need to increase air-flow so that adequate levels of CO2 are maintained and the temperatures inside your indoor garden do not become excessive.

Techniques Using Small Plants

One response to the waning levels of incident energy from grow lamps over distance is to produce smaller plants. Many indoor gardeners prefer to grow larger numbers of small plants in vertical growth chambers. Vertical growth chambers tend to dispense with reflectors all together. Instead the grow lamps are positioned at the center of the indoor garden, sometimes in a ventilated glass cool tube to help keep temperatures within optimal levels. The main task of the ‘chamber’ is to house lots of small plants on its inner edges so that they face inwards towards the central grow lamp fixture(s). This is a far more energy-efficient method of indoor gardening as plants are arrayed 360 degrees around the grow lamp – meaning that a greater surface area enjoys optimum light levels.

Techniques Using Larger Plants

Indoor gardeners who prefer to grow larger plants can array them in rows about two and a half to three feet apart. A reflector-less bulb, hung vertically, can be placed in between each row. It therefore lights the sides of two plants at once! If using 1,000 watt lamps, consider using a light rail to move the lamp up and down in between the rows. Position the lamp level with the mid-height of the plants. Now the whole side portion of each plant is being lit directly by the grow lamp. Additional support and wires may well be necessary to contain and train lateral plant growth so that foliage does not encroach upon the lamp.

Food for Thought

Side lighting allows you to light more of your plant, the whole length of it rather than just the canopy. This will ultimately result in more growth and more bloom so be sure that you have allotted enough space to accommodate it!

I hope that this inspires you to try alternative lighting strategies in your indoor garden. If you have any questions or further advice, please share your thoughts below!

WORDS: Everest Fernandez

Diatoms have been part of our planet’s ecology since prehistoric times. Over millions of years, their remains have accumulated into large diatomite deposits. These diatoms are mined and rendered into a fine, white powder. Natural diatomite is comprised of approximately 65-80% silicon dioxide, 14-18% aluminum oxide, and small amounts of various other oxides including iron, calcium, potassium, titanium, manganese, and phosphorus. Natural grade diatomite is known as ‘Diatomaceous Earth’ (DE) and is often used as a soil amendment and organic pesticide (more on that later!). Diatoms comes from both salt water and fresh water sources, but we’re only interested in fresh water diatomite for horticulture. The salt water DE has a really high salinity level that’s not suitable for plants.

Organic Pest Control

DE may feel like a smooth powder to human hands, but it’s a totally different story if you happen to be incarnated as an insect. When you look at DE under a microscope it resembles a random pile of tiny razors. These ultra-sharp edges cut through an insect’s protective covering, sucking all the moisture out of them until they die! If an insect is stupid enough to try to eat DE this delightful process occurs from the inside out! So aphids, thrips, earwigs, silverfish, slugs, snails, nematodes and fungus gnats beware! You’re on DE’s hit list. Our friendly earthworm is safe from DE’s wrath, however, which is good news all round. DE is less effective in more humid conditions as its moisture-sapping qualities are tempered by the moisture in the air. Many gardeners don’t even bother mixing DE with their soil mix, instead preferring to sprinkle a shallow layer of diatomaceous earth on top of their soil or coco.

Diatomite and Hydroponics

Our fossilized friends are also available in the form of small rocks, rather than a fine powder. These have been heat treated and sterilized. We are aware of three brands on the market at the moment. One is from a place called Maidenwell in Australia, branded “Diatomite.” Another is from the Andes in South America, branded in North America as “Silica Stone.” The same material that is used to create “Silica Stone” is branded as “Diahydro” in Europe. All work well as a hydroponic growth media. Silica Stone / Diahydro stays a little more moist than Diatomite so it requires fewer watering cycles – this is because it has a larger percentage of silica (94%+ compared to 84% for Diatomite), hence the pure white color and the greater absorbency due to increased porosity. You can purchase all brands in various granule sizes. It’s generally recommended to go for small granules of 3/16 to 9/16 inch (2mm to 7mm) or medium granules of 9/16 to 5/8 inch (7mm to 15mm) for hydroponic applications.

So why should hydroponic gardeners be interested in this stuff? Well, it has all the hallmarks of a first-class growing medium. It’s absorbent, porous, long lasting, environmentally friendly, pH neutral, sterile, natural and reusable! As well as silica, it contains other elemental minerals that are essential for plant growth. The plants will uptake the silicate and grow into heartier, healthier plants with thicker stem walls. Manufacturers of the brand “Diatomite” cite that, in side-by-side tests, a 25% increase in production was observed when it was tested against clay pebbles on pepper plants. However, we recommend mixing it 1/3 or 50/50 with clay pebbles when growing in larger pots for increased aeration and a more varied rooting environment. Obviously adding diatomite to clay pebbles affects how you irrigate it. Diatomite holds more water so floods should be slightly less frequent – irrigations every 2-4 hours are advised. If top feeding via drippers using a 50/50 diatomite, clay pebble mix we recommend avoiding constant irrigation in favor of a 15 minutes on, 15minutes off cycle – easily implemented using a standard segmental timer.

Spare us the hype! What are growers really saying about it?

I know what you’re thinking. If this stuff is so great then why isn’t everybody using it, right? So we spoke to real growers who had used it … here’s what they said:

“Works great as a soil amendment. As a hydro media, I’d mix it with something else like clay pebbles as it stays too wet on its own.” – Harley

UGM says: If you’re using this media for the first time, try combining it with clay pebbles for increased aeration. However, we have come across experienced growers who tested it as a hydroponic growth media on its own in gravity fed systems and they found that NOTHING worked as well as small to medium sized DE rocks on their own. Wash it well first!

“If this stuff has microscopic razor sharp edges, couldn’t it damage fine roots?” – Diz

UGM says: The material is very sharp on a microscopic level, but we’ve seen no evidence to suggest that roots are adversely affected. This may be because plant roots grow slowly and the material is light enough so that there is never sufficient pressure or friction for the roots to be damaged.

“I don’t like all that powder in the bags, it will clog my pumps!” – Randy

UGM says: If you put a sponge filter on the intake pump with enough power you prevent this from happening. And remember, this stuff is also used as filtration aids so you really shouldn’t worry about clogging!

“It makes the nutrient solution go cloudy.” – Dan

UGM says: The diatomite particles (diatoms) do not dissolve in water. Even if the water turns cloudy, the material has not dissolved.

“Can’t I just add silicate to my nutrient solution by using a silica liquid product?” – Lisa V

UGM says: You’re absolutely right – you could! Remember that liquid silica additives can raise the pH of your nutrient solution so you may need to pay special attention to adjusting the pH to optimal levels.

Benefits

• High Silica Content – the slow release of silica promotes stronger, healthier plants that can mature more quickly.
• Absorbent – it can absorb up to 150% of its own weight in water.
• Air penetration – the microscopic porous structure of the granules provides aeration and effective thermal insulation to the plant’s root zone. These physical properties provide air movement and prevent root rot.
• Water Cycles – You can reduce the watering cycles to 5 minutes each, 4 times daily due to the retention of solution within the diatomite.
• Preparation for use – Before using, thoroughly saturate the diatomite for about an hour.
• Reusable – After use, you can thoroughly wash the diatomite and then soak in a dilute solution of bleach (1 tbs/gallon) or an algaecide for 24 hours before rinsing and reusing it.

More Usage Tips

• It can be used to replace perlite, clay pebbles, as well as other commonly used hydroponic growing mediums. You can use it in both pots and re-circulating systems. Simply place the growth media in pots in the same manner as you have used clay pebbles or other media of choice. Place roots or seeds in a safe and stable position.
• On both occasions we advise that the granules are rinsed through with water prior to use.
• When using in recirculating systems, there may be some dust which runs down into the nutrient solution. There is no need for concern. Actually Diahydro / Silica Stone / Diatomite are highly efficient filtration aids, so this means there will be no clogging or loss of flow caused by residual dust.
• In order to stabilize the pH, try running some neutral water through the media and measure out pH of the water that flows out. The pH should be somewhere in the region of 6-7. Once this pH measure has been established you should adjust the nutrient solution accordingly. A nutrient solution between 5.5-6.2 should be fine. For example, if the pH of the water run off the growth media is around 7 (extreme case), the solution should be brought down to around 5.5-5.6. Likewise, if the growth media is lower (e.g. 6.2) then the solution can be brought up to about 5.6-5.8. Desired pH should be around 6 in most cases.

Diatomite in Action

A picture tells a thousand words. So we’ll let them do the talking:

SPOT THE DIFFERENCE!

Same nutrients. Same feeding schedules. Same light and environmental conditions. The only difference? Diatomite. Oh, and hugely increased compact growth, shorter inter-nodal spacing and markedly increased overall yield. Get the picture?

Have you got an experience using Silica Stone / Diahydro / Diatomite or any other growth media that you’d like to share with us? Whatever you want to talk about, love it or hate it, tell us about it!

The Australian federal government has refused a request from the country’s tomato industry to import back-up bumblebees into Australia to help them pollinate their crops. Federal environment minister Peter Garrett said he had rejected the request to allow the live import of large earth bumblebees on the grounds that they posed a risk to native bees, birds, and the environment in general.

Garrett cited cane toads as an example of an exotic species which had been brought in to serve a purpose, but had ended up damaging the environment. The nocturnal cane toads were introduced to tropical Australia from Hawaii in 1935 to eradicate cane beetles, which were destroying crops, but the toads also developed an appetite for native species of frog, small reptiles, mammals and birds.

Meanwhile, in the absence of the all-important bees, Australian tomato farmers face the prospect of pollinating endless acres of tomato plants by hand with cotton wool ear cleaners if they’re to enjoy a crop this year! Good luck guys!

Here’s an actual conversation between a buddy of mine, Gary, and a new customer. This is pretty typical of what I’m talking about:

Customer: “My friend has been into hydrotonics for years. Now I want to give it a go too.”

Hydrotonics? Ok, so this guy doesn’t look like the type to be into water-based healing remedies but hey, you never can tell. The customer continues …

“Isn’t that what this shop is all about? Growing plants indoors under lights and stuff?”

Store owner: “HydroPONICS is NOTHING to do with growing plants under lights!”

The customer is taken aback. Confused, he swivels his head around to the grow lamps on display behind him, then he turns back to the store owner as if to ask, “So what the hell are all these grow lamps doing in here then? This is a hydrotonics store, right?”

What is Hydroponics?

Ok. First the Greek: Hydro = water. Ponics = working. Hydroponics, roughly translated, means ‘water working.’ But what does that really mean? Well, some debate still exists over the precise meaning of the word in practice. But the first and perhaps most important principle to understand is that plants grown hydroponically are not grown in soil. If this sounds crazy to you, first understand how things actually work in soil. A plant grown in soil sends its roots into the soil in search of oxygen, water, and nutrients. Soil is generally made up of particles of rock and decaying organic matter. Some beginners think it’s a weird concept to imagine oxygen in soil, but all we’re talking about here are small air gaps between soil particles. Don’t forget: oxygen is absolutely vital to root health!

Plants absorb the nutrients they need via their roots in the form of inorganic ions contained in water. In natural conditions, soil acts as a sort of cache for mineral nutrients. The important thing to understand here is that the soil itself is not the vital thing. You don’t actually need it! You can isolate the mineral nutrients that are present in good soil and dissolve them in water instead. All plant roots need in order to thrive is access to this nutrient solution and oxygen! So soil can be taken out of the equation completely.

You can grow plants in sawdust, coconut husk, clay pebbles, and all sorts of other ‘inert’ substances (inert, in this case, means the substance has no nutritional value in itself). It only becomes viable once you add the nutrient solution. You can even grow plants in the nutrient solution alone – as long as it is well oxygenated. The unifying principle here is this process of taking the required mineral nutrients and adding them to water artificially – this is the basis of hydroponics. The water is doing the “work” instead of the soil.

This begs the obvious question: why bother? Why go to the hassle of getting hold of the mineral nutrients a plant needs and dissolving them in water, instead of just letting the plant get what it needs from soil in the first place?

It All Comes Down To Energy!

Let’s go back to looking at what a plant needs. Above the surface, plants need light and air. Below the surface, plants need water, nutrients and oxygen. Why? Well, light is the motor of photosynthesis. Photosynthesis is the name given to the conversion of light energy into chemical energy. It’s this chemical energy (oxygen and carbohydrates) that a plant uses to develop.

It’s helpful to imagine this energy as a finite resource. If a plant needs to do anything, like grow a new leaf, thicken some stem, produce a flower, fight off a disease or set down a new root, it needs to invest some of that energy. Picture that energy supply getting smaller and smaller as it performs all these energy-dependent tasks.

Continuing with this energy idea for a moment … soil-grown plants typically have to produce larger root systems in order to fully exploit all the nutrients, oxygen and water necessary for them to grow and develop. This takes energy! Now, imagine if all the nutrients, oxygen and water were available directly and close by, without the plant having to create large root systems to find it. It’s a bit like the difference between dialing a number for a pizza to be delivered to your house instead of walking to the shops, buying the dough ingredients, toppings, grating the cheese, and cooking it for yourself. If a plant doesn’t need to invest lots of energy into creating huge root systems it can redirect that energy towards producing more stems, leaves and flowers – which, in turn, creates more energy! Do you get my exponential drift here? More energy spent on creating leaves that, in turn, generate more energy!

So this is one of the reasons why plants grown in hydroponics develop faster than soil-grown plants. They don’t have to spend so much energy creating roots to find nutrients, oxygen and water in the first place!

Keep Stress to a Minimum

Let’s look at another aspect. A common problem with soil gardening is over or under-watering. Or in other words: not enough oxygen (because the soil has become compacted or saturated with excess water), or not enough water. Under-watering is less of a common problem. However, many gardeners who grow using containers experience it. Not enough water dries out the root hairs, causing them to die. This, in turn, stunts growth. Both over and under-watering cause your plants to suffer from stress and increase the likelihood of disease.

Plants grown in an active hydroponics system have access to nutrients, water and increased levels of oxygen all the time! There’s no perpetual ‘too wet, too dry’ stress – meaning plants can get on with the business of growth and bloom rather than wasting precious resources on self-protection. Growing plants in hydroponics is a far cleaner environment too – there is far less potential for harmful pathogens in a hydroponics solution than in soil.

Finally, let’s not forget that you can far more easily control the nutrients your plants have access to in a hydroponic environment because you are totally responsible for it! (There are two sides to this coin however … certainly soil affords the grower greater margin for error!)

To sum up then, here are some advantages of hydroponics over soil:

• Increased control over the plant’s rooting environment
• Hydroponic systems cut down on your manual labor
• Water can be conserved through recirculating the nutrient solution
• Smaller root zone means less floor space required
• Faster growing time means you don’t have to wait so long between harvests
• Pest, weeds, and diseases can be more easily prevented / controlled
• Hydroponic plants do not have to deal with soil borne pests
• Much higher yields!

Bob Taylor, chief chemist of Flairform (www.flairform.com), explains why…

Multi-part nutrient guidelines

1. Do not combine concentrated nutrients in too little water.

Think about it for a second. Two and three-part nutrients come in separate “parts” for a reason! If they come into contact with each other when still concentrated (or in too little water) you will see a white precipitate form (Fig 3.1) and, depending on the formulation, this can happen well within a minute or so. Try this for yourself – mix an equal volume of each part in a glass, undiluted. You’ll quickly see precipitate start to form. The majority of the precipitate is typically calcium sulfate. Now, add more water and see if it will dissolve. The longer you delay dilution, the more difficult (or impossible) dissolution becomes. Your plants can only use nutrients that are fully dissolved in the water. So all that precipitate represents food that your plants can no longer access. Along with poor pH control, this is a cause of the white precipitate within the body of the nutrient (Fig 3.6b). Therefore, to prevent this, always add the majority of water before combining nutrients. Additionally, always stir well before each subsequent part is added. Note that the source of white precipitate above the water line, on the surface of media and equipment (e.g. clay pebbles), is salt deposition from evaporation. Notably, the amount of precipitation from this source is greater at higher (EC) nutrient concentration.

2. Which comes first: A or B?

My advice is that you should always add the part containing the phosphate first. This is because the addition sequence of each nutrient ‘part’ can affect nutrient stability, particularly if your water has high alkalinity. “Alkalinity” (bicarbonate & carbonate) is the component of natural waters that causes high pH. Adding the nutrient dose to high alkalinity water can decrease the stability of several nutrient species (including calcium, sulfate, iron, copper, manganese, zinc). Therefore, rather than trying to pre-adjust the pH of the water (often a very difficult task – pH adjustment is better done after all nutrients and additives have been added), it is preferable to first add that part of the nutrient that lowers pH the most. This is usually the part that contains the phosphate. In two-part nutrients this is usually part “B”. So there you have it. “B” comes before “A” after all! However, make sure you check with your particular brand. Note that the “part” without any phosphate will normally have relatively little impact on pH. Secondly, it usually contains the iron, which is highly unstable at pH levels much above ~6.5. Note: in three-part nutrients the phosphate is sometimes dispersed across two bottles. Therefore, if you really want to be accurate, determine which contains the highest concentration of phosphate, and add that first.

3. Add equal amounts of each part.

Avoid “roughly measuring” out the nutrient dose. An excess of one nutrient species does not compensate for deficiencies in another. In the case of a two-part, ‘under’ dosing part ‘B’ (for example) could cause a deficiency in over half the nutrients required (i.e. P, K, S and all of the trace elements excluding iron). This problem is compounded with two and three-parts because the dose volumes for each part will be roughly one-half to one-third (respectively) of what it would otherwise be if using a one-part. Therefore, without appropriate measuring equipment, when small tank volumes are being used the dosing error can be significant.

To some growers, the additional complexity of two and three-part formulations is an interesting challenge. To others, who want to make their lives a little simpler, the idea of dosing using multiple parts isn’t so appealing. Certainly, using a high quality one-part formula readily ensures an optimal balance of nutrients and, as a result, one-part nutrient products are increasing in appeal among growers.

Whatever type of nutrient you prefer, you should always follow these dosing guidelines:

Thoroughly stir the nutrient.

Always stir immediately after the addition of nutrient, additives or top-up water. Doing so will eliminate high zonal concentrations of the less soluble nutrient species. Further, it removes zones of extreme pH (either high or low), thereby preventing the destabilization of nutrients that are unstable outside of the optimum pH window of 5.0-6.5 (Fig 1.11).

Be diligent with pH.

This is probably the most crucial area of nutrient management.

Be cautious when using additives with a high pH.

I don’t mean to be alarmist here as it’s important to note that essentially all additives will affect nutrient pH at least slightly. The best technique to adopt with those that elevate pH significantly (e.g. silica, PK additives) is to add them to the water and adjust the pH down to ~6 prior to adding the nutrient. Another less preferred but common alternative is to pre-dilute the additive in a separate volume of raw water prior to adding to the nutrient solution, then quickly lower the pH to below 6.5 once this solution is added. Note that a white cloudy precipitate (calcium sulfate) may form when the pre-diluted additive initially merges with the nutrient solution (Fig 3.6a). However, because the initial particle size of the precipitate is small, it will usually re-dissolve if the pH is immediately re-adjusted.

For further information, see www.flairform.com or post your questions and comments below!