Stonewool is made from molten basalt rock spun into a dense, candy floss like material. It is a popular substrate used by hobby gardeners and commercial growers alike. This growing media is available in small and large starter cubes, round plugs, slabs and mini cubes.
It is important to pre-soak the media with a nutrient solution with a pH of 5.5-5.8 once before use, as this helps to neutralise any particles that may be left over from the manufacturing process. The substrate is inert and therefore can be used as hydroponic growing media.