Grow media serves two main functions in hydroponics: to supply oxygen to plant roots and also to physically support the actual plant. There are so many different grow mediums you can choose to use for your hydroponic or aquaponic gardens. Understanding the benefits of some of the options could help you decide which would be the best fit for your system. It is outlined below four of the many options in regards to its benefits and nuances (pros and cons):
Expanded Clay Pebbles
Clay is one of the most abundant substances on earth. This grow medium is made by heating clay at extremely high temperatures to create a very light and porous material. It is pH-balanced and completely reusable. Make sure to clean the pebbles in hot water and wash them in order to free them of dust and debris. In order to reuse them, you must simply sterilize it and it is ready to go. Expanded clay pebbles do an excellent job in aerating plant roots because of its lightness.
Pros: Lightweight, Porous, Reusable, pH-balanced, water-retaining
This type of media is composed of granite or limestone rock, which is heated at extreme temperatures and melted. Once melted, it is then spun into a wool-like texture that makes it extremely light. These are usually then shaped into cubes of various sizes. In order to use rockwool, soak it in pH-balanced water for a minute and then squeeze out the excess water. The major benefit of using rockwool is that you can plant a seed directly into the cube and you will not have to worry about it floating away or getting lost in the water supply.
Pros: Lightweight, Porous, Inexpensive, pH-balanced
Cons: Non-reusable, water-retaining (chance of root rot if soaked for too long)
Who isn’t cuckoo over coconuts? Coconut fiber is from the husk of coconuts – you know, that brown fiber material that covers the delicious fruit. Coconut media comes in different sizes. The fiber is much smaller in size and chips are much larger, which allow for more airflow. Although it is great at aerating the roots, it is possible for it to retain too much water. Proper draining is essential when using this grow media.
Pros: Lightweight, Porous, Inexpensive
Cons: Non-reusable, water-retaining (chance of root rot if soaked for too long), Not pH-balanced
Finding river rock is extremely easy as they sell them at any aquarium or home improvement store. One could even use rocks found in his/her backyard as long as they sterilize it first. Because they are not porous, they do not retain moisture for as long as porous materials, but it also provides great airflow. This could be the cheapest option for the beginner hydroponic/aquaponic gardener as most people can find them for free. A big downside could be that it is extremely heavy, so moving systems once it is set up would be very difficult.
Pros: Inexpensive, Easy to find, Reusable, pH-balanced
Cons: Nonporous, Heavy, Does not retain water
In my aquaponic and hydroponic kits that I sell, I use both rockwool and expanded clay pebbles for my grow media. My favorite type of grow media to use is expanded clay pebbles. I love its lightness and it is also aesthetically appealing. The rockwool is meant to hold the tiny seed in place during watering and the expanded clay pebbles take up the rest of the room in the net pot.
Click here to purchase a Mason Jar Aquaponic Kit from my Etsy shop.