Growing Media
The growing media is the structural support for the plants you will be growing. When growing the conventional way in soil, the soil is the main support system the allows the roots to anchor the plant in place. Since hydroponics is growing without soil the roots would have nothing to support them if not for the growing media. The growing media in hydroponics is usually inert, does not have any nutrients or chemical properties, it is important that you supply the plants proper nutrients and water.
There are several different options to use in Hydroponics. The following sections will go into details for clay pebbles, Hydroton®, and Rockwool.
Rockwool
For Hydroponics, Rockwool can be purchased in a sheet of many small cubes that can be separated by cutting them out. Each cub usually has a hole in the top of it for a seed to be placed in. Rockwool has been used for many years as a insulation material that is made from volcanic rock and is inert. It is like a sponge with tiny holes and passages that allow roots to grow through.
The picture above shows several plants that have recently germinated in Rockwool. Each of the above pieces of Rockwool can be cut to separate the plants from one another. This is a good media to start your seeds in as the plants can stay in the rockwool and still be transplanted into other types of Hydroponic media or soil if you prefer. The Garden Station by Nomis Engineered, Inc. uses this type of media.
When growing plants in Rockwool it is important to keep the sides and bottom of the Rockwool dark to not stifle root growth.
For more information on planting seeds in Rockwool, please see our YouTube video.
Clay Pebbles or Hydroton®
In Hydroponics, the clay pebbles are usually used for larger plants but can be used for any plants. The clay pebbles are also inert. Water flows around them very easily, which aids in drainage and allows for aeration. The pebbles cannot store water, so they are usually used with hydroponic systems that have water flowing through them or have the water levels rising and lowering.
The picture above shows some seedlings growing out of the clay pebbles. Once a plant starts growing in the clay pebbles it will be very difficult to impossible to transplant it.
If using clay new clay pebbles it is important to rinse them thoroughly as there is usually a lot of small particles and dust on them that can cause problems in a hydroponic system with pumps and tubing. The small particles and dust are created from the manufacturing process and from them rubbing together during transport. If reusing clay pebbles, they should also be cleaned thoroughly since they might have pieces or roots or leaves in them that can cause problems in a hydroponics system.