An Introduction to Hydroponics and Hydroponic Systems

How does a hydroponic system work?

In a hydroponic system, a soil-free medium is used to keep the plant in place. Options for this medium include sand, stone, or fiber. Because these are porous, they enable the absorption of air and water, which is required for plants to grow.
Typically in a hydroponic system, nutrition is efficiently directed to the roots of the plants. Thus, there is no need for the plant to expend its energy in developing long roots. As long as they are exposed to light, hydroponic plants will flourish.
What are the different types of hydroponic systems?

There are six different types of hydroponic systems. A brief description of each is given below:
Wick System

This is the simplest of the hydroponic systems. A rich nutrient solution is pulled into the growing medium with a wick. Coconut fiber, vermiculite, perlite, and pro-mix are used as growing mediums. This system works best with smaller plants because the wick can only supply a limited amount of water.
Water Culture

This hydroponic system consists of a styrofoam platform that holds the plants, while floating on a nutrient solution. Nutrients and oxygen are filtered to the plants' roots by an air pump. This hydroponic system works best for plants which thrive on water, such as leaf lettuce. As with the wick system, the water culture system is not ideal for larger plants that require a more efficient feeding cycle.
Ebb and Flow

The ebb and flow system operates by temporarily flooding the plant's grow tray with the nutrient solution and then letting it flow back into the nutrient reservoir. The cycle is controlled by a pump that is activated by a timer. This hydroponic system is more versatile than the previous two.
Drip System

This hydroponic system is widely used because it involves a simple operation. A timer is used to turn on a submerged pump that enables the nutrient solution to reach the plant via a thin drip. A recovery drip system recycles excess solution that is not absorbed by the plant; a non-recovery system allows this to go waste.
Nutrient Film Technique

This technique uses a constant flow of food so no timer is used. A tube is used to pump the nutrient solution into a tray where it can be absorbed by the plants' roots. Any solution that is not absorbed automatically flows back into the reservoir. Typically, the plant is placed in a basket whereby the roots can hang freely into the solution. No other growing medium is required.
Aeroponics

The technology involved makes this the most complicated of the hydroponic systems. No medium is used as the roots grow in air, but are misted with a nutrient solution according to a precisely timed schedule every few minutes. The misting cycles need to be monitored to avoid the roots drying out.

Ryan Karl is an expert horticulturist who writes extensively on gardening topics. He is especially interested in all aspects of hydroponics, or the science of soilless gardening.