NATURAL HYDRO

Story by Cees Van Wingerden Just because you grow indoors and utilize chemical fertilizers doesn't mean you can't take advantage of what Mother Nature has to offer. While the perfect feeding regimen alone will not recreate the great outdoors on your ebb-and-flow table, there are several products on the market that fill in some of the gaps. I admit it. I am drawn to products that are "natural" and believe in utilizing them to the max. I know it's not very PC to admit, but I am not a "back to nature" kind of guy. I've been known to spray a pesticide or two in my time, so my interest in natural products is based purely on their potential to enhance the quality and yield of plants. There are some dynamite products on (or soon to be on) the market that can help supercharge your indoor garden, and whether your are "organic" or not, they are well worth investigating.

I see a lot of confusion among indoor gardeners with respect to how to integrate "natural" products into their growing. Some of it is caused by lack of information. Some of it is caused by the wrong information. As most of us don't have the time to go back to school and get a degree in plant biochemistry, it might be helpful to talk a little bit about the science behind "natural" products and how they fit into a normal production scheme.

This discussion has absolutely nothing to do with natural (i.e. organic) fertilizers. I am speaking about "natural" products used as additives or adjuncts to traditional hydroponic production practices--things like mycorrhizae, seaweed extracts, amino acids, humates and chitosan. I use "natural" parenthetically because: 1) I don't like the word "organic," and 2) I tend to throw a few synthetic products into the mix as well. (I already told you I'm not the back-to-nature type.)

Rather than classifying these products by their chemical structure or biological pedigree, I think it's easier to classify them by using a more artificial structure. I divide them into "natural products," "naturally derived" products and "inducers." "Natural products" may be "alive," like mycorrhizae, or not, like worm castings. Seaweed extract, of course, is the classic "naturally derived" product, containing cytokinins, amino acids and minerals. "Inducers" are products that cause shifts in plant metabolism, resulting in effects such as disease resistance, stress tolerance or yield enhancement.

The biggest myth surrounding natural products is that they are somehow incompatible, practically and philosophically, with traditional hydroponic culture. Traditional hydroponics calls for fine-tuned nutrition based on exact ratios of mineral fertilizers. It's the system most often employed by indoor gardeners. The "roots" of the system can be traced directly to research out of Europe (mainly the Netherlands) that established hydroponic culture as the preferred technique for greenhouse vegetable production worldwide. Scientists discovered that by using artificial growing media and supplying all nutrients directly to the plant, yields could be achieved that were 16-20 times those achieved by field growers.

Unfortunately the large scale of the business also introduced a very dogmatic infrastructure, complete with huge manufacturing companies who jealously guard their position in the market. For many years "the dogma" decreed that scientists had achieved almost all that was possible in the area of nutrition, and so nutrient additives or conditioners, aside from a few foliar fertilizers, were relegated to the realm of pseudoscience and snake oil. As the "home" of hydroponic horticulture, this dogma was strongest in the Netherlands, where to this day, crop consultants and growers alike have difficulty dealing with any new product or technology not created in Holland.

The reality is that the most consistent results in hydroponics are achieved using the traditional mineral-fertilization system. But there is something missing. When we "came out of the dirt" we were able to fine-tune plant nutrition, but also we had to leave out the "intangibles." Why is it that some soils are better for onions and some are better for wine grapes? Why do certain coniferous trees do well in nurseries, and then suffer greatly from diseases and pests when planted in the forest? Bingo! There must be something in native soils beyond the basic nutrients that affects growth, yield, fruit quality, onset of fruit production, nutrient availability, etc.

Natural products are the missing link. We can make all the pH, EC and N-P-K ratio adjustments we like, but we can't make up for the fact that mycorrhizal fungi evolved in nature to enhance phosphorus assimilation in plants. And what about humic and fulvic acids, the main components of soil humus, responsible for "natural chelation" of micronutrients and enhanced plant uptake of macronutrients? So, you see, the marriage between traditional mineral-based hydroponic culture and "natural" products is not one of convenience, but one of necessity.



NATURAL HYDRO - page 2

So let's talk about a few products that fall into the three categories I mentioned earlier. Remember that I chose to divide them into "natural products," "naturally derived products" and "inducers." Just a short while ago, most products on the market could easily fit one of these classifications. Now, our marketing friends have thrown us a curve. They mix things together! Do marketers look at us and rub their hands with glee? You betcha! But an educated consumer is a good consumer, so please continue.

NATURAL

This is a real pot-luck category that includes worm castings, biofungicides, bioinsecticides, mycorrhizae, critter guano, humic acid (for those who don't think it belongs in the derived group), and various microbial preparations. Among the biofungicides, I wish that I could tell you that bacillus subtilis, a bacterium that controls pythium and botrytis, is currently available (it is not). For anyone familiar with the chemical fungicide Ridomil®, some isolates of B. subtilis have been shown to be just as effective against pythium species on a number of crops.

Our mainstay biofungicides are based on trichoderma species (fungi) and pseudomonas species (bacteria). Trichoderma is a predominantly soil-borne fungus that out-competes other fungi for space around plant roots, and so offers protection by simply excluding the bad actors. Interestingly you have two choices with trichodermas--you can purchase actual fungicide preparations, or use coir (coconut husk) substrates.

Coir contains natural populations of trichoderma species, both in the compressed growing slabs and in the "loose" medium in bags. Be aware, however, that the new molded (not compressed) 4" coir blocks sold under the Prism® and Sunleaves® labels, while excellent for propagation, are steamed and hot-water-leached during manufacturing, which eliminates the fungus. Their slabs and loose coir, however, do contain abundant levels of trichoderma species, as do those of other manufacturers.

Mycorrhizae are another additive that can provide a boost in growth. These are fungi that are found in nature forming symbiotic relationships with plant roots, and they aid in phosphorus uptake from the soil. Their fit in hydroponic production still has not been determined, but there is no doubt that mycorrhizae are beneficial to indoor gardeners using organic substrates like peat or coir. There are numerous sources of mycorrhizae, but my personal preference are those from Plant Health Care® (PHC), including Mycor™Flower Saver™ Plus, a cocktail of mycorrhizae and beneficial bacteria. PHC was started by Dr. Donald Marx, world-renowned for his research on mycorrhizae and plant-microbe interactions, and the company's products are based on solid research.

NATURALLY DERIVED

This is the killer category. This is where the marketing guys have you by the balls. There are a lot of good ingredients, some good products and a few "bathtub specials" in this group. As a savvy consumer, you will want to take a close look at labels, comparing the manufacturer's claims with what they actually put in the jug. If the manufacturer does not list the product components (sometimes this is done to avoid potential conflicts with pesticide and fertilizer regulations). contact them directly and quiz them on the contents. The most common additives include cytokinins (usually from seaweed), amino acids and vitamins (vegetable extracts and seaweed), humic and fulvic acids (produced from fossilized carbon deposits), various auxins (IAA, IBA, IPA), and cellulosic materials (cellulose is the main component of plant cell walls).

One of the best bets in this category is a combination of zeatin (increases cell division in roots), glycine, betaine and other amino acids (reduced plant stress); humic and fulvic acids; plus a nitrogen and potassium booster to adjust for sudden accelerated growth. The product is called Growth Activator® and is one of three nutrient conditioners sold under the RUSH® brand. Not incidentally, the manufacturer holds several patents on the Growth Activator constituents, because they were able to prove that their proprietary formulation results in a synergistic yield response, greatly exceeding yields of plants treated with simple mixtures of the active components.

INDUCERS

Inducers are the most interesting, least understood and least common of the three categories. I say they are misunderstood, because they sometimes can appear to be inconsistent. Twenty-percent yield increases are not unheard of, yet sometimes they do "nothing." The problem: The observed result is greatly affected by the external environment. If the plants receive "perfect" nutrition, if they are not attacked by pests or pathogens, and if the day and night temperatures are just right, then, you may not see large increases in yield or quality with the use of inducers. However, how often does everything go according to plan?

The best-known inducer is chitosan. Chitosan products are based on chitin, the principal cell-wall component of fungi, also found in the exoskeletons of crustaceans, such as shrimp. When chitosan products are sprayed onto plants, the plants "think" they have been attacked by a fungus. The plant's cellular machinery kicks in, eliciting biochemicals to stave off infection. In the process, the plant shifts from vegetative growth to a generative habit, putting most of its energy into producing flowers and fruit. One of the more effective products available is called RAGE™, and is based on a patented chitosan called marinosan. Used by one of the largest greenhouse-tomato growers in North America, this product has produced yield increases over 18%.

The other inducer of interest is gamma-aminobutryic acid (GABA). When plants are under any kind of stress, they naturally produce GABA. Unfortunately, if the stress, pest or pathogen is of sufficient magnitude, the plant cannot make GABA fast enough to be effective. A small company in Michigan has developed a patented product that contains a synthetic GABA, which when applied to plants, induces sustained, high levels of GABA in the foliage and leaves. This results in resistance to heat, cold damage and pathogens, as well as increases in sugar content, shorter time to harvest and higher yields. Unfortunately, GABA is not yet available to the market, but that problem should be corrected shortly.