Hydroponic gardeners interested in growing plants without soil have a number of different systems available to them. Hydroponic systems provide higher yields, superior quality and are easily adapted for accessible gardening by people in wheelchairs.
Nutient Film Technique
Nutrient Film Technique (NFT) systems are the most common hydroponic systems in use today. In theses systems, a thin film of nutrient flows continuously through narrow channels or gulleys. Nutrient circulated through the channels by pumps in a central nutrient tank. Plants are placed in openings in the top of the channels that allow enough space for the plants to receive the optimal amount of light for growth. The most common crops grown in NFT systems are lettuces, herbs and other leafy greens.
Floating Raft System
Floating raft systems consist of tanks 12 or more inches deep filled with nutrients. Seedlings are inserted into polystyrene boards which float on top of nutrient solution. As the plants grow, the roots extend into the nutrient solution beneath the raft. Floating raft systems typically operate like a production line. New plants are introduced at one end of the tank on a regular schedule, typically once or twice a week and are pushed forward until they are ready to harvest.
Flood and Drain System
Flood and drain hydroponic systems consist of individual plant containers or shallow trays filled with a free-draining aggregate such as gravel, expanded clay or rock wool. The containers are flooded and drained periodically with nutrient pumped through an inlet on the bottom of the container. Almost any kind of plant can grow in flood and drain systems, with taller plants such as tomatoes or vines such as cucumbers supported by wires. Flood and drain systems are used primarily by hobbyists or very small commercial operations.
Drip systems consist of individual plant containers or shallow trays, channels or troughs filled with an inert growing media such as perlite, expanded clay, coco coir or rockwool. A complete hydroponic nutrient solution is supplied to the surface of the media through small emitter tubes. Pumps are used to supply the nutrient through small emitters on the high side of sloped channels. The irrigation schedule varies according to the needs of the crop and environmental conditions. Drip systems are very commonly used for large commercial hydroponic production of tomatoes and cucumbers.
Wick systems are the simplest of all hydroponic systems. They consist of media-filled growing containers, troughs or shallow trays set over a reservoir. Nutrient solution is drawn up to the plants by capillary action through a wick. Wick systems are typically used only in very small hobby operations.
Aeroponic systems are the most technologically advanced hydroponic systems which use foggers, sprayers, nebulizers or misters to deliver nutrients directly to the plants' roots which are suspended in a chamber above the nutrient solution. Aeroponic systems are primarily used by hobbyists and small growers and are not commonly used on a commercial level.