In a hydroponic garden, you grow plants without soil. Soil normally provides your plants with their water and nutritional needs. In a hydroponic system, a growing medium is used and you supply the water, nutrients and structural support. Different hydroponic systems deliver water in various ways, and the best one for you depends on the time, space and money you're willing to invest in your system.
Hydroponic systems both water and feed plants at the same time. To prepare the nutrient solution, you dissolve nutrients especially make for hydroponics systems into the water. As plants absorb the water with their roots, they take in the nutrients as well.
Hydroponic systems range from simple non-recycling systems in which you hand-water the nutrient solution into a draining plant bed, to highly automated aeroponic systems. In general, there are two types of hydroponic systems. Aggregate systems hold plant roots in an inorganic substrate, such as perlite or rockwool. Periodically, you flush water and the nutrient solution through the growing medium, where it comes into contact with plant roots. Water culture systems dispatch with the growing medium and suspend plant roots directly in the nutrient solution that provides them with their minerals and water.
In addition to water and nutrients, you need to also consider how your hydroponic system will provide oxygen to plant roots. Plants cannot sit constantly in water or they will die. Most systems, such as the nutrient film system, provide plants with a periodic reprieve from water soaking their roots. Other systems, like the aeration method, in which plant roots sit directly in the nutrient solution, bubble oxygen constantly into the system. You should also consider the potential for disease forming on damp plant roots. According to the Alabama Cooperative Extension, this can especially pose a problem in aeroponic systems where plant roots receive periodic misting from a nutrient solution.
You can construct basic systems like the non-recycling and ebb-and-flow--both aggregate systems--and nutrient film water culture system easily from items found around the home. Other systems, such as the aeroponic system, require more specialized and expensive equipment.
Ease of Use
Also keep in mind the convenience of the system that you choose. Easy-to-build systems like the non-recycling or ebb-and-flow often require you to manually water the grow bed one to three times per day, which can become tedious or impossible, even, depending on your schedule. More advanced systems water and feed the roots automatically using timers and pumps.