Growing medium is essentially required in hydroponic gardening to anchor and support the root system. It holds moisture and nutrient solution while providing excellent oxygen flow for the plants. There are various types of growing mediums being used in hydroponic gardening. Each growing medium works differently and is favorably for different types of hydroponic systems.
Hydroton is lightweight expanded clay aggregate, commonly known as LECA. It is very stable with pH neutral and it does not affect the pH of the nutrient solution. Hydroton is a fast draining medium that doesn’t hold excessive water. The grow rocks supply the root zone with plenty of oxygen and they work perfectly well for an EBB and Flow type hydroponic systems.
Rockwool is getting popular as one of the growing mediums for hydroponic gardening though its original usage was in constructions as insulation. The rockwool used in hydroponic gardening is of horticultural grade. It is mostly used for drip-style hydroponic systems.
Horticultural rockwool is produced by melting a combination of rock and sand at high temperature. The mixture is then spinned and pressed into different sizes and shapes. As rockwool comes in various sizes and shapes, this makes it the most versatile growing medium for hydroponic gardening. Its ability to retain 10 times as much water and hold more than 15 percent air at all times also make it more favorable in any hydroponic systems.
However rockwool must be handled with care when used in hydroponic gardening. It has a high pH and is sensitive to pH shift. Your nutrient solution has to be adjusted in order to achieve a neutral pH for the root system. Besides that, you should wear dust or particle mask when handling as fibers and dusts from rockwool are hazardous to your lungs.
Vermiculite, perlite, glasswool and sands are among other common growing mediums used in hydroponic gardening. They are stable and do not usually effect the pH of the nutrient solution. Though their tendency of retaining too much moisture might restrict them to only be used with plants that are suitable for this condition.
You can also combine the various rocks, perlite, vermiculite, sand or anything that you could imagine to make your own growing medium. This not only practical but also inexpensive. You may have to experiment each of the combination to get the right growing medium for your own hydroponic gardening system.