"Hydroponics" is the term used to describe a gardening system that replaces soil with a substrate like perlite, coarse vermiculite, sand or gravel. Because soil itself is merely a support system for plants and a carrier for nutrients---and sometimes pests and diseases---it is possible to eliminate it from the gardening equation while supplying nutrients directly to the root system in a more readily available, water-soluble form. The Alabama Cooperative Extension System outlines the key provisions of hydroponic growing systems as support, oxygen, carbon dioxide exchange, water, nutrients, and adequate light and warmth.
Begin with a small gardening project such as an herb garden. Once you have gotten the hang of hydroponic gardening, try your hand at something more difficult.
Decide if you prefer a recycling or a nonrecycling system. A recycling system collects and recycles the nutrient solution that you apply daily to the roots, while a nonrecycling system collects the nutrient solution that drains from the substrate and you dispose of it. It is not necessary to use a recycling system, but considering that you will be applying nutrient solution at least three times daily, it makes sense to recycle as much as you can.
Put together a hydroponic growing system with a container with a drainage outlet, a hose (for a nonrecycling system) and a collection bin. If you build a recycling system, eliminate the hose, and replace it with a large collection pan beneath the box. To recycle the solution, simply pour it from the pan over your plants.
To build a slightly larger scale recycling system, the Alabama Cooperative Extension System recommends raising your container off the floor---by placing it on a table, for example---and tilting it by placing a brick under one end so the solution drains into a receptacle that you can then use to water the plants. This way, you don't have to remove a pan from underneath the container each time you want to water the plants.
Choose your substrate material (which will replace the soil). The substrate should do the following: support the plant's roots, hold moisture and nutrients, and aerate and drain properly. Choose from coarse sand, gravel, perlite, coarse vermiculite, or rock wool. Perlite and vermiculite are sterile and readily available, whereas sand or gravel will have to be washed thoroughly before planting to remove any lime or other impurities.
Choose your plants. Plants that produce fruit, like tomato or pepper plants, require a lot of water and light, and demand a lot of attention. The amateur is better off trying his hand at indoor hydroponics by growing something that also does well indoors in soil; herbs are a good choice for the beginner.
Purchase a nutrient solution at your local garden center. The nutrient solution contains water-soluble nutrients that must be applied to the roots of your plants. A good rule of thumb is to flood and drain the media three times per day. Keep the roots moist.
Provide adequate light for your plants. This is usually done with the help of one or more grow lights, especially if you are growing in the winter and sunlight is scarce.
Keep a steady temperature of 70 to 80 degrees for warm-season plants during the day and 60 to 70 degrees at night. Cool-season plants will do well in temperatures about 10 degrees cooler than that.