Stonewool Slabs 40x40x40mm

Stonewool (also known as rockwool) is a natural mineral growing medium, produced by spinning molten basalt rock into fine fibres and pressing it into blocks. Because it is manufactured under high heat, it starts out completely sterile and free of pests, weed seed and disease, so no additional sterilising is needed before use.

Growers value stonewool because it holds no soluble minerals of its own, which makes nutrient management straightforward, particularly when paired with a balanced hydroponic feed. It also strikes a good balance between water retention and air movement around the root zone, and tends to run warmer than a soil bed, which suits propagation and winter growing where consistent root zone temperature matters.

These 40x40x40mm slabs cut down into 36 individual cubes, the largest of our three sizes. The extra root room suits sturdier seedlings or slower growing crops that need more time in the cube before transplanting. They work across NFT and flood and drain systems as well as traditional propagation trays, taking plants from first root through to a size ready for transplanting with minimal root disturbance.

Available as a single slab, packs of two or four, or a full carton for larger propagation runs.