Hydroponic Growing Mediums

Just like with traditional gardening, there are many choices when it comes to growing mediums for hydroponic gardening. Factors like what kind of hydroponic setup you choose to go with, what type of plants you’re growing, and the amount of space you have will help determine which growing medium is best for you. 

Below are the three main types of growing  mediums used in a hydroponic setup along with their pros and cons. 

1. Sponges – Pictured above is an example of a growing sponge with a small lettuce sprout beginning to spread its roots throughout. Sponges are great for setups that are tight on space and can be used for almost any hydroponic method including drip systems, aeroponics, and NFT setups.

Most sponges are 100% compostable and are soft enough for the roots to easily spread through. Sponges are not re-usable, as the roots of the plant will completely take over the sponge.

Sponges are great at wicking up and holding water, thus delivering a constant supply to the roots regardless of the hydroponic method used. This growing medium is the least expensive compared to rock wool and clay pebbles and readily available in many sizes. We use these on Amazon in the Solaris Garden hydroponic systems and Solaris Seed Starter.

2. Rockwool – Rockwool is the most popular medium used, especially in large scale hydroponic green houses. Rockwool gained its popularity from its ability to insulate the roots well and maintain a high retention rate for water and oxygen. It is also very durable, meaning it won’t be likely to break down in your hydroponic system.

As for rockwool’s downfalls, it is not a biodegradable product and it can not be composted, its durability and density also make it harder for roots to spread throughout easily. It is also high in pH, which means you will have to monitor your pH levels in your setup more consistently when using this growing medium. Rockwool pairs best with drip and NFT hydroponic systems. Rockwool cubes are not re-usable once a mature plant has grown in them.

3. Clay Pebbles – Last but definitely not the least, clay pebbles are a great growing medium for beginners who may have a very simple hydroponic setup in a bucket or similar container. Clay pebbles are very porous leading to great aeration of the root system.

The clay pebbles release oxygen and water as the roots need it without ever over soaking the root system (unless your plants are sitting in water without any air gap). Clay pebbles are 100% natural and can uniquely (compared to other growing mediums) be reused over and over again! Clay pebbles won’t hold on to as much water as other growing mediums, making them a great choice for plants that require good drainage. This growing medium works best in a drip or NFT hydroponic system. Like mentioned before, you can also use them to grow plants in a bucket with a pump at the bottom to circulate the water throughout the container. 

One of the many great things about hydroponic gardening is the fact that you can purchase a complete turn key set up or buy separate parts to build your very own unique creation. Either way you choose to go, determining which growing medium is best for the path you choose to take, is the first step for ultimate growing success. 


Solaris Systems Team

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