Gardening with rockwool plugs

Gardening with rockwool plugs

Article by Anne Harvester

When you’re shopping for growing mediums either online or at a local hydroponic supplies retail store, you’ll find a number of different ones from which to choose. Despite the fact that hydroponics means growing indoors without the use of soil, growing mediums are still a necessary part of the process.

Different Types

Growing mediums can be almost anything. Nevertheless, the most popular choices for growing indoors 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

We placed rockwool at the end of the list because this is one of the most common choice among hydroponics gardeners due to its versatility and ease of use.

Originally, rockwool was invented for use as home and building insulation. The first hydroponic gardeners that realize the usefulness of this substance were those living in Denmark; since then, it has become commercially available for use in hydroponics in two forms: rockwool cubes and rockwool cubes. The manufacturing process is similar to that of cotton candy; once stone and sand has reached the melting point, the fibers are spun into many different sizes and shapes.

The Advantages of Rockwool As a Growing Medium

rockwool cubes come in sizes up to 36″ by 12″ by 3″ and can easily be cut into the desired shape. It is extremely porous, able to hold tremendous amounts of air and water – so should your water pump fail for any reason, whether by shutting down or providing too much water, the roots of your plants will be safe long enough for you to take corrective action.

If you prefer, you can purchase rockwool plugs as well. These are small granules that stick together quite well, so messes are avoided.


All hydroponic supplies have their advantages as well as their drawbacks, and rockwool is no exception. It is not especially environmentally friendly; being made of rock, it does not bio-degrade, therefore care must be used in its disposal. It can also present a health hazard if improperly handled; rockwool dust in the lungs can cause silicosis. It’s important to wear a face mask with approved HEPA filter when working with rockwool.

Finally, rockwool as a very high pH level; therefore, you’ll need to amend it with some kind of acidic substance and monitor pH levels on a regular basis.

As far as growing mediums are concerned however, rockwool’s light weight and ease of use make it a fine choice for use in hydroponics. Take sensible precautions, and it can be one of the best growing mediums around.

About the Author

Anne Harvester has a great deal of experience with indoor gardening. Hydroponic gardening is the way of the future. Known to some as “soil less gardening”, hydroponics are proven to grow plants 20-30% faster than their soil grown counterparts.

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