Growing hydroponically means without soil using a nutrient solution to feed plants. Plants grown hydroponically produce quickly and the systems are environmentally friendly. Building and maintaining a hydroponic system---especially one large enough for food crops---requires knowledge, experience and can be capital intensive. The four common hydroponic growth methods differ in how the nutrient solution is delivered to the plants, but share other components including a growing tray, containers, growing medium and liquid nutrient container.
A wick hydroponic growing system works well for small plants like herbs and is the simplest system to setup and operate. The wick system uses two containers, one tray for the plants or plant pots and growing medium (the plant tray) and the other for the nutrient solution (the reservoir). Several wicks, usually made of nylon or cotton rope, are looped at the bottom of the plant tray with the other end dangling into the nutrient solution.
Wick systems rely on capillary action to draw the solution from the nutrient reservoir into the plant tray. Wick hydroponic growing systems are passive meaning the solution is always present and there are no moving parts.
Ebb and Flow Systems
Ebb and flow, also called flood and drain systems, have two trays similar to the wick system. However, in the ebb and flow system, a pump is placed in the nutrient reservoir that pushes solution through a tube into the plant tray flooding it with nutrients. At the opposite end of the plant tray from the flooding tube is a drain tube that recycles the unused solution back into the reservoir.
The pump in an ebb and flow hydroponic growing system is attached to a timer set to flood the plant tray every 30 minutes or one hour depending on the needs of the plants. Some ebb and flow systems also use a air stone to add oxygen to the reservoir.
Drip hydroponic growing methods are similar to ebb and flow systems with a pump submerged in a nutrient solution that pushes nutrients up to the plants. However, drip systems send the solution through small tubes, called drip manifolds, which drip the solution onto the growing tray rather than flooding. Excess solution is drained back into the reservoir.
Nutrient Film Technique (NFT)
The NFT hydroponic growth method is the most productive or highest yield system. In an NFT system, the plants are placed in a pipe or gutter that is gently sloped. The roots dangle free into the pipe where a nutrient solution runs constantly pumped from a reservoir to the top of the pipe. Excess solution is drained back to the reservoir. The advantage of the NFT system is the constant availability of oxygen to the plant's roots without using an airstone. But like the ebb and flow system, the disadvantage is the reliance on a working pump. Any loss of electricity or mechanical failure will quickly lead to plant death.
All hydroponic growing methods require monitoring of nutrient pH which is critical to the plant's ability to use nutrients. Plants are placed in a plant tray or containers filled with soilless mixtures such as rock wool, perlite or vermiculate to support the plants. Grow lights are required in hydroponic growing systems to ensure that plants receive at least 12 hours of light per day. Temperatures must be controlled at the appropriate range for the plants.