Hydroponics (from the Greek words hydro (water) and ponos (labour) is a method of growing plants using mineral nutrient solutions, without soil. Most people who are new to hydroponic gardening, assume that plants are always grown in water. That is certainly one way, but there are many other choices for media. Hydroponics is really just soil-less plant growing, with some other substance providing the support and nutrients fed in other ways than through earth. One of the most obvious decisions hydroponicists have to make is which medium they should use. Different media are appropriate for different growing techniques.
ROCKWOOL
Rock wool (mineral wool) is probably the most widely used medium in hydroponics. It’s a type of basalt that is specially processed to provide a strong, porous base. It’s mostly inert, so it won’t decay or leach compounds into the water. It provides good drainage; it’s lightweight and inexpensive. Despite its lightweight and porous nature, rockwool provides a very sturdy medium for growing plants. It gives good support to developing roots. At the same time it helps regulate the water temperature by being a good heat conductor. Adding rockwool will alter the pH of the environment slightly at first, but this is easily controlled using a pH kit. Though rockwool has many advantages for a hydroponic gardener, most everyone will want to experiment with different media at some time. There are many more options available.
SAND
Ordinary beach sand is one common medium. It drains well compared to ordinary clay-infused soil, but in a hydroponic setting it doesn’t do as well as most other possible media. But it’s extremely easy to use and certain plants take to living in sand very well.
GRAVEL
Ordinary aquarium gravel is used in some settings. It provides a strong, clean supporting medium that can also be attractive. Gravel is inexpensive, easy to keep clean, drains well and won’t become waterlogged. However, it is also heavy, and if the system doesn’t provide continuous water, the plant roots may dry out.
PERLITE
Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles. It’s desirable for its ability to retain air. Since hydroponically grown plants will quickly deplete any dissolved oxygen, perlite will help the pump keep the water oxygenated.
VERMICULITE
Like perlite, vermiculite is another mineral that has been superheated until it has expanded into light pebbles. It draws in water from passive systems by capillary action, helping automate the watering and nutrient feeding tasks. Since it holds even more water than perlite, it may exclude air so it needs to be used in moderation. A mixture of perlite and vermiculite is often used for that reason.
COIR
Coco peat, also known as coir or coco, is the leftover material after the fibers have been removed from the outermost shell (bolster) of the coconut. Coir is a 100% natural grow and flowering medium.
Hydroponic gardening can be fun. Experiment and try some of the different options. See what works best for your plants.
Joyce Boulan is the owner of a website where you can find more information about Hydroponic Gardening, articles of interest and find everything you will need to begin this fun hobby. Please visit: All About Hydroponics