Hydroponics is the process of growing plants without soil. In some hydroponic systems, this means suspending the plants with their roots submerged in a hydroponic nutrient solution. In others, a soil-less medium, such as expanded clay pellets, acts as a support for the plant and nutrients soak through to the roots, similar to soil planting. The type of hydroponic system you use depends on the plants you want to grow and your available space.
The wick system is the simplest hydroponic system to set up. It is passive, with no moving parts and no electricity required. Wicking material runs from the liquid nutrient reservoir into the soil in the growing bed. This wicking material pulls the nutrient solution up into the soil, keeping the soil moist and providing constant nutrition to the plant roots. Larger plants that require a lot of water may not do as well in this system, because they will use the nutrient solution faster than the wicks can bring more up from the reservoir.
Water culture is another simple hydroponic system. It consists of an aquarium or other container filled with hydroponic nutrient solution with an air pump and air stone constantly oxygenating the solution. A platform floats on top of the solution, and plants grow in baskets with their roots submerged. This system works best for water-loving plants such as lettuce. Large plants or those that grow long-term won't do as well with their roots submerged.
One of the most common hydroponic systems, the drip system uses a timer to control a submersible pump. The pump pushes nutrient solution to drip lines that drip the solution at the base of each plant. This systems has two forms. The recovery drip system collects excess nutrient solution that runs off the growing bed and directs it back into the reservoir. The non-recovery system does not save this runoff, requiring more frequent fills.
Ebb and Flow
An ebb and flow hydroponic system, also called flood and drain, periodically floods the grow bed with nutrient solution, then drains it back into the reservoir. The grower can either perform the flooding manually or set the system up with a pump and timer.
Nutrient Film Technique
Nutrient film technique, or NFT, provides a constant flow of nutrient solution to the plants. The growing tray is usually a tube lying on its side at an angle, so that it slopes from one end to the other. The plants rest in holes along the top with their roots hanging inside the tube. A pump constantly pushes nutrient solution up into the high side of the tube; the solution flows over the roots as it runs down to the low side and back into the reservoir. Because this system usually does not use a growing medium to support the roots and retain moisture, even a brief power outage can result in the roots drying and killing the plants.
Aeroponics is a high-tech form of hydroponics in which the grower suspends the plants with their roots hanging into a dark chamber. The system mists the roots with hydroponic nutrient solution every few minutes. An aeroponic system uses a timer with a short cycle to control the misting frequency. Like NFT, this system can result in plant death if a power outage occurs and the misting cycle is interrupted.