Many hydroponic systems, such as our Foody 8, use grow medium in place of soil. Grow medium gives plants support while still allowing roots to grow and water to flow through. Here are a few of our favorites:
1. Expanded Clay Pebbles
One of the most popular type of grow medium, expanded clay pebbles are a great value if you plan on growing hydroponically for an extended period of time. They are made by putting some bits of clay in a kiln and expanded. You can find them online and at gardening stores. We like them because they fit nicely into our net pots and is a good price when you buy large quantities.
Rockwool is another commonly used grow medium. It has a texture similar to cotton candy and is made from rock that has been strung into strands. It does need to be soaked in pH balanced water before use, so there is some prep work required.
3. Coco Fiber
Coco fiber is made from coconut husks, meaning that is completely organic. It retains water well, but also allows for plenty of air flow to roots. It's not as common as the other grow mediums on this list, but has been rising in popularity in recent years.
Perlite is heated volcanic glass that looks like tiny white rocks. It is sometimes used in potting soil, but can also be used for hydroponic systems. It does float, so it doesn't work in all hydroponic systems. It is also covered in a dust that is unhealthy to breath in, so it needs to be rinsed off before use.
There are other grow mediums out there that you can read about here.