HortiWool™ is a man-made mineral fiber generally used for insulation. However, modifications to the manufacturing process rockwool will support and, under the right handling practices, promote plant growth. Melting basaltic rock and spinning the melt into fibers manufacture rockwool.

It can be used alone in pots or as an amendment to organic based mixes. Water absorbent granulates can be used as a substitute for peat in media where the peat breaks down rapidly such as in orchids and bromeliad production or in cases where disease transmission in peat is rapid. The addition of water absorbent granulate to peat mixes at 20-50% volume increases water holding capacity and aeration, improving plant growth and shelf life. It is recommended for use alone or mixed with water repellent granulates, depending on the air/water ration required. The water repellent granulates are substituted for aerators such as perlite and styrofoam. Granulated rockwool will not break up under severe soil mixing; the perlite or vermiculite do and it can withstand the heat of sterilization under conditions that melt styrofoam.