Its All About The Roots

Root systems vary in size from those of a seedling, perhaps a few inches long, to those of a 300' redwood that can grow larger in size than the visible tree itself! Regardless of the physical size of the plant, roots serve three essential functions: (1) the uptake of water and nutrients; (2) storage for manufactured materials; (3) providing physical support for the plant above ground. Hydroponics is all about healthy roots! The absorption of water and nutrients takes place just behind the root tip through tiny root hairs. These root hairs are extremely delicate and usually die off as the root tip grows further into the medium. The method in which the roots absorb water and nutrients is called diffusion. In this process, water and oxygen pass into the root structure through membranes in the cell walls. An interesting point is that diffusion actually takes place at the ionic level, which in laymen's terms means nutritional elements are passed by the electrical exchange of charged particles. This fact can lead to confusion over whether hydroponics is unnatural and is not at the level of "organic quality" because plants grown using hydroponic methods are not fed "organic nutrients." The true bottom line is that roots can ONLY uptake PURE ELEMENTS, no matter what the original source is. In other words, in the process of feeding, plants can't absorb organic material unless it is first broken down into pure elements, no matter where it comes from. Since a hydroponic system is generally cleaner than a composted organic growing environment, the hydroponic system itself provides a superior growing environment. But also remember the first principle of hydroponics: GIGO. Garbage in, garbage out. A hydroponics system is only as good as the nutrient its being fed with.

When thinking about plant roots, oxygen is rarely the first thing that comes to mind. But oxygen is crucial to root health. Oxygen is absorbed by roots and then utilized for growth, and in return, the roots give off Carbon Dioxide. The absence of oxygen in the root zone will cause asphyxiation, which in turn will damage the roots and will adversely affect the top of the plant as well. Stagnation of water in the root zone also causes asphyxiation, in addition to root rot. Once plant roots die, or they become dehydrated, death of the organism is usually imminent. Many studies have proven that oxygenation to the root zone is a major factor in determining a plant's growth potential. In fact, the practice of "Aeroponics" as a growing method has been developed to maximize growth one step beyond that conventionally believed to be possible with hydroponics. Plants grown aeroponically actually have their roots suspended in mid air!

Aeroponics teaches us that plants can function normally with their roots exposed to light, provided they are always at 100% relative humidity. However, exposure to light also promotes the growth of algae. Algae appears as a green or brown slime on roots, plumbing, and containers. Some studies have suggested that plants suffer when their roots are exposed to light, however this is probably mostly due to the resulting algae growth on the surface of the root. Algae will compete for both water and nutrients, as well as oxygen. To be on the safe side, I recommend using opaque containers and avoid the use of transparent materials for tubing and reservoirs, for any hydroponic system. Dark colors such as deep green, deep blue and black work best at blocking stray light. You should also note that plant roots are extremely delicate and should not be handled.

You will, at some point, need to transplant seedlings or cuttings into your hydroponic garden. Just be patient and gentle, and keep roots wet. In the event that roots begin to obstruct proper flow and drainage in your system, you may have no choice but to adjust their position, which may cause damage if you are not careful. It's of utmost importance to maintain sufficient humidity around your plants' roots at all times. Low humidity will cause dehydration and root dieback. However, you also do NOT want to leave your roots soaking in STAGNANT water, as this will cause the roots to die from lack of oxygen. Dieback is visible in the form of dry, browned, and sometimes decaying roots. Once your plants' roots die, there is no method to revive them. If the damage is serious, your crop stands a slim chance of surviving.

Hydroponic Slime
Roots at left are from a 45 day old hydroponic cucumber grown in a low quality nutrient solution. The roots at right were fed with a premium quality nutrient solution.
Growing Soilless

Growing Soilless

This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.

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