When you’re growing plants without using soil, you have to replace it with something. There is a myriad of options to choose from and some are more popular than others. There are different benefits to each particular medium. Important factors include water absorption, pH balance, and support for the plant. Some options include sand, rice hulls, composted pine bark, or even foam insulation. What follows are some of the more popular options that growers choose regularly.
Probably the most common growing mediums for hydroponics, Rockwool can be considered the “OG”. It is composed of granite and/or limestone that has been superheated and melted then spun into small threads. Some benefits of using this medium include its porous nature and the fact that it is sterile. It is very popular for starting plants or starting clones. In order to make sure it’s pH balanced, you should soak it in pH balanced water before using.
Also known as “grow rock”, clay pellets are another popular option with hydroponic growers. The main benefit of these pellets is that they can be reused. They are also heavy enough to support the plants. Airflow and workability are a couple of additional benefits of using this medium. Clay pellets have a neutral pH and can be found at almost every hydroponic supplier.
This sustainable by-product of coconuts is a popular choice of the earth-conscious grower. Allowing more oxygen while retaining more moisture, this medium is beginning to edge out the two previously mentioned options. An additional benefit of using coconut fiber/chips is their plant-stimulating hormones. These help to protect plant roots from infection and disease.
Rocks, often sourced from rivers, are a popular option because they are cheap (sometimes free). What the grower saves in cost, they gain in extra attention and maintenance. A popular method is to mix rocks with another medium, such as coconut chips. When using a flood and drain system, rock is both cost-effective and drains well.
Each hydroponic grower has preferences when it comes to a growing medium. Depending on the method of growing, different mediums have clear advantages. Doing your own research and talking to more experienced growers will help to send you down the right path. Over time, experimentation and time will help you find the right growth medium for you.