What Makes a Good Growing Medium?

What Makes a Good Growing Medium?

One of the terms often used in regard to hydroponics is growing medium. Growing media are one of the most used materials for growing crops in greenhouses and hydroponic systems. Media such as soil in traditional cultivation funnel water and nutrients to plants’ root systems—but what makes one medium productive may not be what makes another work. In hydroponics, for example, you are not limited solely to soil. Learn more about what makes a good growing medium below. We’ll mention three factors that we believe lead to solid growing media. Keep in mind that every horticulturist is different, so you’ll want to do your own research to determine which medium matches your needs.

Keeps an Even Air-to-Water Ratio

In our previous blog, we talked about how soil can often drown a plant’s roots. With the right growing medium, you won’t have to worry about that as much because the medium will keep an even ratio of air to water. Now some media are better than others because of their water-holding capacity and their air porosity. Water-holding capacity refers to the volume percentage of water that’s retained after the saturated medium is allowed to drain. The air porosity is the volume of pore space that’s occupied by air after the water is allowed to drain.

These two factors can make it or break it for successful growth. If your plant doesn’t have enough water because the medium didn’t retain it, that’s an issue. At the same time, if your medium keeps all that water but doesn’t leave enough space for air, then that’s just as much of an issue. Finding this balance is essential to a good growing medium.

Best media for this characteristic: perlite, coconut coir, and RockWool

Helps Protect From pH Changes

Another aspect you’ll want to look for in a good growing medium is how it helps protect the root and the plant from pH changes. Over time, as plants and root systems are subject to nutrient solutions that filter in and out, the pH may vary. You don’t necessarily want that to happen to your plants. This means you want a growing medium that will help combat any pH changes.

A neutral pH for a medium is ideal, as it won’t affect the pH of the solution as it goes to the roots. When mixing growing media, be cautious about their pH—you don’t want one that’s too acidic, as that will mess with the root growth.

Best media for this characteristic: perlite, vermiculite, and expanded clay pellets

Has a Solid Cation-Exchange Capacity

A growing medium’s cation exchange capacity (CEC) “is an inherent soil characteristic and is difficult to alter significantly.” Simply put, the CEC is what influences a medium’s ability to hold on to essential nutrients. One of the goals of a hydroponic solution is to have a plant’s roots take in the nutrient solution—this can ultimately be affected by the CEC. When you’re looking for what makes a good growing medium, the cation exchange capacity plays an essential role.

Best media for this characteristic: vermiculite and RockWool

For all of your growing medium needs, turn to FloraFlex. We have RockWool growing medium, nutrients for your solutions, containers, and so much more. Reach out to see how much faster your garden can grow with solid hydroponics and parts.