Plant Food...Keep them Healthy

At the end of his fourth year of medical studies, Darren was halfway through his final exam when he came upon this question:

"Name the three advantages of breast milk."

Without skipping a beat, he wrote down: One…it contains the optimum balance of nutrients to ensure healthy growth for the newborn child, Two…as it is contained within the mother's body, it is protected from germs and helps develop the child's immune system, then found he was stumped for the third answer. He wracked his brain scouring for the third elusive advantage of breast milk when inspiration hit him:

Three…it comes in such nice containers.

Although the container doesn't really matter, the fact is simple. Your hydroponic garden needs breast milk. Now, before you break out the breast pump and bee-line for the nearest maternity ward, I am speaking metaphorically. Nutrients are the key component to a healthy, successful hydroponic garden. In essence you are the pusher, and your plants need their fix, baby.

Hydroponically grown plants do not have to chew their food. That is, their root systems have easy access to the nutrients necessary for growth, and these nutrients are available in their base, liquid forms. This speeds the plant's digestion of these nutrients without them having to be broken down or siphoned off. Because your plants will not have to waste time searching for food, chewing their food, or watching Baywatch, they can spend more time growing out of the clothes you buy them. The ungrateful little bastards. There are sixteen elements needed for plant growth, which are known as macronutrients and micronutrients. Plants extract several of these elements, such as oxygen, carbon, and hydrogen, from water and air. The rest of the elements must be made available through the nutrient solution you supply to your plants. Macronutrients, by definition are the more important nutrients for your plant's growth. The distinction between macronutrients and micronutrients are made based on how much of each nutrient your plant really needs to process to stay alive. Macronutrients are again split into two divisions: Primary and secondary. The primary macronutrients are nitrogen (N), phosphorous (P) and potassium (K). The secondary macronutrients are calcium (Ca), magnesium (Mg) and sulfur (s). Micronutrients, or trace elements as they are commonly referred, are iron (Fe), manganese (Mn), boron (B), molybdenum (Mo), zinc (Zn), copper (Cu) and chlorine (Cl). These micronutrients are used in very small amounts, much like dental care to English people, and are sometimes extracted by your plants from impurities in the water or your choice of substrate (ie: rockwool, pea gravel, etc.). Each of these nutrients has a job to do. Just think of them as the essential parts of a balanced breakfast. Your plants will thank you for them. Again, except in some limited experience, I am speaking metaphorically. But do remember to keep your plant's breakfast balanced. There is such a thing as too much of a good thing.

The various primary and secondary macronutrients all carry out very important tasks in tandem to keep your plant healthy. It is this symbiosis that really makes the art of hydroponic gardening into a careful balancing act.

Nitrogen is central to the development of new leaves and stems as well as to overall growth and performance. New leaves and strong stems allow the plant to process light more successfully. Remember, it is a house of cards. All parts of your plant's ecosystem are co-dependant on their fellows. If one part of that house of cards falls, the whole house may fall. An overabundance of nitrogen can cause soft, weak growth and can also delay the production of fruit and flowers. Conversely, watch out for yellowing leaves and weak, spindly growth of stalks and stems. These are symptoms of a nitrogen-light nutrient solution. If you notice any of these symptoms, adjust the nitrogen level of your nutrient solution accordingly.

Phosphorus is necessary to the plant's photosynthesis (The transformation of light energy to chemical energy) as well as the production of flower and seeds. If you notice older, mature leaves turn a deep green or exhibit mottled brown or purple spots, your plant's phosphorous levels are too low. Also, if your plant's growth appears stunted, or chlorosis (an unhealthy yellowing) occurs on the lower leaves, it may be time to doctor a new mixture for your reservoir with a little moew phosphorus.

Potassium and beer: They aren't just for breakfast anymore. Okay, beer still is. However, your plants will need a requisite amount of potassium to remain healthy. It is necessary during the entire growth process of your plants, contributing to their formation at every stage, but most importantly during fruit development. Think of potassium as the foreman at the production plant; it is inherently involved in the manufacture of sugars, starches and chlorophyll. Potassium also regulates the stomates in the plant's leaves and helps build strong roots. The stomates consist of two guard cells that form a small pore on the surface of the leaves. Like louvers, these guard cells control the opening and closing of the stomates in response to the stimuli available in the plant's environment such as light, heat, moisture, humidity….in essence, the bouncers at the Chloro-drinkyer-phyll nightclub. Watch for mottling and/or yellowing of the mature leaves on your plants, most commonly found along the leave's margins, as this is a sure sign of potassium deficiency. If you notice the pre-mature dropping of flowers or fruit, this may also indicate an unsatisfactory level of potassium in your plant's diet.

Ask your dentist; calcium doesn't just build strong bones and teeth. It is also essential to the manufacture and growth of a plant's cells. Really, your dentist would know. They are a veritable fountain of knowledge. Aside from being critical in the fundamental buildup of your plants, they also share the bouncer's position with potassium, but at a different level. If your soil, nutrient or grow medium is excessively rich in nutrients, calcium acts as a buffer storing the excess that your plants cannot process. Sort of a first line of distress…and they say Colgate is an action hero. Symptoms such as the curling and stunting of young, immature leaves, or dieback at the shoot tip are indicative of calcium deficiency. On the flip side, too much calcium in your plant's diet can stunt the plant's overall growth.

Magnesium is fundamentally involved in the absorption of light energy making it central to the structure of the chlorophyll molecule. Simply put, it regulates the amount of sunlight or manufactured light that your plant is allowed to "drink". If your plant exhibits curled leaf margins, the yellowing of mature leaves (with the veins remaining green) or in advanced cases the unnaturally bright green coloration of growing tips on new leaves and stalks, there is a good chance your plant is hurtin' for some magnesium lovin'.

Sulfur is an acidic mineral, which is also involved in the chlorophyll process. However, it doesn't directly influence the process. It acts as a support system making the light available to the plant more easily processed; a facilitator of sorts. Plants in a low light area can get a much needed boost up by the inclusion of the correct amount of sulfur in their diets. If you notice young, immature leaves turning a pale green while the older leaves retain their healthy hue, or the stalks appear stunted and spindly, this could be due to a sulfur deficiency.

Toxicity levels in macro or micronutrients can also cause harm to your plants. Keep those plates spinning, Bobo, this is one serious balancing act. What follows are some of the most obvious symptoms your plants may exhibit due to toxic levels of nutrient being too high for your plant to process:

Nitrogen: Long internodes with crispy, brittle stalks.

Iron: The leaf edges appear dark in contrast to the rest of the appendage.

Manganese: The veins of your plant's leaves appear dark brown. Also, your plant may show the classic symptoms of Iron deficiency (the upper leaves develop interveinal chlorosis with green veins) as an overabundance of manganese inhibits iron uptake.

Zinc: The appearance of veinal chlorosis starting in the middle leaves.

Boron: Necrosis of the leaf edges, turning them brown, dry and brittle.

The availability of commercially formulated nutrients widens daily as the popularity of hydroponics and its advantages spreads across the globe. Ask your local Hydroponics retailer for any information they may have on the products they carry. Or, of course, you can play Mr. Wizard and make your own witch's brew should you be adventurous enough.

There are 3 or 4 key components you will need to doctor your own brew: A container large enough to hold the amount of solution you are interested in preparing, a Ph tester, a scale capable of measuring the individual portions of chemicals you are about to combine and of course, the actual chemicals themselves. During the formulation and upkeep of your nutrient solution, it is very important to keep the Ph at an optimum level, with most plants preferring a slightly acidic solution varying from 5.5 to 6.5 on the scale. Through transpiration (the digestion of your solution by your plants) and evaporation of your solution, the Ph balance can drastically change, so keep a constant measure. You can obtain Ph test kits in a range of forms from your local gardening or hydroponics store. If your solution becomes too alkaline (Ph 7.0 or greater), add a few drops of white vinegar per gallon and re-test. If your solution is too acidic (5.0 or lower) then add a few pinches of baking soda per gallon, and again, re-test. When the bed fits just right, invite the three bears to come home and don't make any future plans.

What follows is a basic recipe to make 10 gallons of nutrient. Try it at your leisure, and make the adjustments necessary to yield a batch equivalent to your desired amount.

Chemical Compound Grams (Level Teaspoons)
Ammonium phosphate 8.7 (2)
(NH4H2PO4)
Potassium nitrate (KNO3) 19.0 (4)
Calcium nitrate
(Ca(NO3)2 * 4H2O) 22.3 (4 ½)
Magnesium sulfate (Epsom salts) 18.6 (4)
(MgSO4 * 7H2O)

Mix these ingredients in 10 gallons of Ph tested water. Then mix the following two micronutrient solutions separately, and combine with the 10 gallon main tank:

(1) Mix 7.6 grams (1-1/4 level teaspoons) of boric acid (H3BO4) and 0.6 grams (1/10 teaspoon) of manganese chloride (MnCl2 * 4H2O) in 1 quart of water. Use 1/2 cup of this solution for 10 gallons of macronutrient solution. (2) Mix 3 grams (1/2 level teaspoon) of chelated iron (NaFe EDTA) in 1 quart of water. Use 1-3/5 cup of this solution for 10 gallons of macronutrient solution.

Once these 3 mixtures are fully combined, re-check your Ph and make any necessary adjustments. This solution can be circulated for 10 to 14 days, as long as it is flooded one to three times a day. If your system circulates its nutrient on a more regular basis, this duration will of course be shortened. After this time, flush your substrate with clean water and allow it to drain several times to wash out any accumulated minerals which may cause toxicity problems. Mix and add a new solutiona nd you are off to the races again. Its like the Shampoo bottle says in all its Zen-like glory: Wash. Rinse. Repeat.

Now if you will excuse me, Baywatch is on.