Hydroponics is the science of growing plants without soil in water containing high levels of dissolved nutrients. Hydroponics is often used in areas with limited water and soil resources, such as Israel and arid regions in Africa. Forms of hydroponic gardening were practiced in pre-Hispanic Mexico with the floating Aztec gardens of Lake Tenochtitlan. Modern hydroponics vary in design and complexity. Hydroponics systems are described as wick, water-culture, ebb and flow, drip, NFT, and aeroponic. For a complete description of hydroponic systems with diagrams, see this site.
Hydroponics has the advantage of using very little water, up to one-tenth the water of traditional gardening. Hydroponics constantly circulates water and nutrients so evaporation is the only loss of water. It has the additional benefits of working very well indoors and producing very fast-growing plants. Plants raised with hydroponics typically exhibit high yields, high vitamin and mineral content, excellent flavor for fruits and vegetables, and higher levels of essential oils.
Hydroponics systems often use a growing medium such as sand, stone, or fiber to give the roots support. In addition, special growing lamps and air pumps may be necessary depending on the yields you wish to achieve.
In countries such as Mexico and the Netherlands, hydroponics is used on a large scale to grow anything from flowers to tomatoes for export. Small scale low-tech hydroponics has been introduced successfully in third world countries to help feed urban populations with great results. You can find out more about these projects here.
This is a cool outdoor hydroponic planter that you can use in your back yard or a sunny spot to grow flowers, fruits or vegetables without needing soil at all. It would also work great on a sunny balconey or patio.
Want to know more about Hydroponics?
Wikipedia has a comprehensive page on hydroponics including the origins and history of hydroponics, advantages and disadvantages of growing with hydroponics, and irrigation techniques. Check out the chart comparing crop yields from hydroponics to traditional soil growing methods. It also covers different types of media, nutrient solutions and commercial hydroponic techniques.
Hydroponics.com has a wealth of information on hydroponics news, hardware and gardening instructions. There is a wealth of information in the how-to articles section. There is also an education section that contains the answers to common hydroponics questions.
Hydroponics BC explains the ins and outs of hydroponics, with articles on nutrients, lighting, CO2, insect control and many other topics. It also has a brief link list and a summary of recent hydroponic news.