Soilless plant growing can be traced back to the 1600s. Hydroponic crop production was used in the 1940s to feed troops. Hydroponic growing was able to move into commercial production when plastic was developed in the 1960s. Today there are six basic types of hydroponic gardening: wick, water culture, ebb and flow, drip, nutrient film technique and aeroponic.
According to Simply Hydroponics and Organics, wick hydroponics is the easiest system because it has no moving parts. This system houses plants in a tray with a sterile growing medium. There is a reservoir below with nutrients. A wick draws the nutrients up to the growing tray. Wick hydroponics is not well suited to larger plants such as tomatoes because the nutrient feed is used through the wick too quickly.
Water culture is an inexpensive system that is simple to build and maintain. Plants rest in a tray that floats over water so their roots dangle in the nutrient solution. An air pump with an air stone adds the oxygen the plant needs. Simply Hydroponics and Organics says this is a good system for growing lettuce or other plants that love water. It not the right choice for long-rooted or large plants.
Ebb and Flow
Ebb and flow floods a growing tray with a feeding solution, then drains the solution back into the reservoir. This system is able to utilize a variety of growing mediums and pots that allow the plants to be moved around. Ebb and flow systems use a pump to move the feeding solution up to the plant tray and a timer to control how often the plants are fed. This system is good for larger plants such as tomatoes.
A drip system uses a drip emitter at each plants' root system to deliver the nutrient solution. The system can be set up to collect the excess nutrient liquid or not. A timer is used to turn on a pump in the reservoir, allowing the system some flexibility. A system that recovers the nutrient liquid needs to be tested regularly--it will have changes in nutrient strength. Drip hydroponics, like ebb and flow systems, works well with larger plants.
Nutrient Film Technique
Nutrient film technique (NFT) is best for growing lettuces, greens, oriental vegetables, herbs and edible flowers. Crop King defines NFT as a system that uses a thin layer of nutrient solution that flows over the roots of the plant. A small piece of growing media is used in the early stages of the plants' growth to ensure the seed does not wash away.
The Growing Edge defines aeroponic as a misting process that floods the plants' roots with a nutrient feed solution. The liquid that is not used by the plants is collected and recycled. Aeroponic systems can be set up to spray continuously or in timed intervals. Aeroponics works well for broccoli and cabbage. Its biggest advantage is that is uses less water.