Hydroponic methods of gardening have been used for hundreds of years and are the preferred method for many gardeners. Over the past few decades, many different types of hydroponic systems have been developed. These systems vary with the way the plant's nutrient solution is circulated, with the type of medium and the type of reservoir used. Hydroponic systems can be purchased from most hydroponic stores, or you can make them with supplies from any hardware store.
The most ancient form of growing plants hydroponically was accomplished by digging holes around a garden area that was suffering from drought. Clay pots that had several small holes around them were set in the holes. The clay pots were then filled with water from other sources to provide moisture to the soil surrounding the crop. Today electricity is often used to pump or circulate nutrient water to the roots of the plants. Technology has drastically changed the process of hydroponics and continues to do so.
There are many types of hydroponic mediums that are used today. Clay pebbles, pea-size gravel, perlite, lava rock and rockwool are the most common mediums. These mediums are usually placed in a net pot and then placed in a reservoir of some type. All of these mediums work the same, except for rockwool. Rockwool is a more expensive medium that is known for holding the optimal balance of moisture and oxygen that plants require. Therefore, during a power outage, the plants in the rockwool will not dry out as fast as the plants that are in other growing mediums. All these mediums listed are reusable, which makes them a one-time purchase.
A very basic form of hydroponics uses a nylon rope that has one end buried in the medium surrounding the roots, with the other end submerged in a nutrient solution. As the moisture content by the roots decreases, the nylon rope will pull the nutrient solution out of the reservoir, up to the plant. The only watering that this type of system requires is filling the reservoir before it runs dry. Rockwool or a sand and soil mix will work well with wick systems. These types of systems are easy to build, and require very little maintenance.
Drip systems work well with all forms of mediums. This method requires a water pump to constantly pump a nutrient solution over the top of the growing medium. As the water is supplied to the top of the root structure, it drains off the bottom of the roots into a reservoir where the nutrient solution is circulated back to the top of the growing medium. This method is good for beginners and for those who are experienced with hydroponics.
The aerospring method of hydroponics is the most advanced form of growing plants hydroponically. It involves an airtight reservoir, like a 20-gallon plastic container with holes cut on the lid for the net pots to sit in. As the roots hang down through the net pots, a nutrient solution is sprayed over the roots. The reservoir must be airtight because the humidity must stay at one-hundred percent. This method is the best for growing, because the roots have constant access to air and nutrients. Any nutrients that are not needed by the plant will simply run off of the roots and be recirculated.