AO36/40 – 98 starter cubes
Grodan – Stone wool
Stone wool is a natural product. It is made from Basalt, solidified lava spewed from the innermost depths of the earth. In the mid-nineteenth century, American geologists on Hawaii discovered a “woolly” material consisting of stone threads, which the local inhabitants were using to insulate their huts. This was a volcanic material, the product of red-hot steam being forced through liquid lava under high-pressure.

To produce stone wool commercially, Grodan/Rockwool duplicated this natural process as closely as possible. Today, extracted basalt is re-liquefied in furnaces at a temperature of 1,500 °C. The liquid Basalt is then spun into threads in spinning chambers, and then congealed in a hardening kiln using hot air (230 °C) and compressed into wool packets, which are then cut into slabs, blocks or plugs and packaged in film. With factory processing, one cubic metre of basalt can produce approximately ninety cubic metres of stone wool.

The advantages
The use of stone wool substrate offers many advantages. Thanks to the controlled manufacturing process, this growth medium is of a consistently high quality. The sterile production under extreme temperature ensures that the product is clean and sterile. Its unique hydrophilic fibre also makes the cultivation on stone wool substrate very easy to control. The grower can administer the amount of water and nutrients the crops need in a very directed and controlled manner, to achieve optimal growing results. Waste becomes a thing of the past. Efficient use of water and nutrients keeps yield per square metre high, and energy consumption per unit of product low. Additionally, the product is lightweight, making it easy to use. And last but not least, stone wool can be easily re-used. To sum up, it is a sustainable and environmentally-friendly product.