You’ll find a wide range of growing mediums at most retail outlets that carry hydroponic supplies as well as websites through which you can order hydroponic supplies. Hydroponics is a form of gardening that is usually done indoors and without soil, but growing mediums are still necessary.


What Are The Choices?

If you’re planning to do your growing indoors, you find a number of growing mediums from which to choose. Among the most popular are:

- Expanded clay pellets
- Oasis Cubes
- Coconut Fiber
- Sand
- Gravel
- Perlite
- Sphagum Moss
- Water
- Vermiculite
- Fiberglass Insulation
- Sawdust
- Proprietary Soilless Mix
- Air
- Lava Rock
- Rockwool

The last one is available in two different forms: rockwool cubes and rockwool plugs. It is also the most popular and commonly used by those whose gardens are growing indoors.

About Rockwool

Originally used as home insulation, it was the Danish hydroponics community that first thought of using it as one of their growing mediums.

Contrary to what you may have heard, rockwool is not obtained from stone sheep; it is made from melted sand and rock, which is then spun into fibers (such like “cotton candy”) that can be made into numerous useful shapes and sizes.

Advantages of Rockwool

Rockwool has distinct advantages over other types of growing mediums. Among these is the fact that in holds a substantial amount of water; in addition, almost 20% of rockwool cubes or plugs consists of air.

These two facts protect your efforts at growing indoors in two ways:

(A) It provides a “safety buffer” in case of power outage or pump failure

(B) It provides the roots with sufficient oxygen, making it impossible to over-water.

Rockwool cubes and rockwool plugs are easy to work with as well. It comes in many different sizes – up to 1’ by 3’ slabs three inches thick. You can also purchase loose granules of rockwool. Since it sticks together, it is easy to avoid the creation of large messes.

Disadvantages

As with all hydroponic supplies, there are certain drawbacks to rockwool as well. Disposal of used rockwool is a problem, as the substance is practically indestructible – and therefore, not bio-degradable. It requires at least 24 hours of preparatory soaking before it is ready for use, and since it is very alkaline, you will need to adjust your nutrient solution and monitor pH levels regularly.

Finally, growing mediums such as rockwool and vermiculite can health hazards. Vermiculite is sometimes contaminated with asbestos, and rockwool dust can cause silicosis if ingested into the lungs. As long as proper precautions are taken however, rockwool can be one of the most easy-to-use growing mediums available.