Rockwool is a sterile, inert growing medium that is perfect for growing seeds and cuttings.
Rockwool is made by a process that's similar to making cotton candy. Molten rock is poured over a spinner forming cotton candy like fibers that are then pressed and cut into blocks.
The fiber construction of Rockwool Cubes have a unique water holding ability that strikes an even balance of air and water - perfect for nurturing new root growth in tender cuttings or seedlings.
Rockwool has capillary properties that pull moisture and nutrients up to the seedling or cutting from the bottom. Watering new seedlings (or cuttings) is easy because you simply pour water into the tray - not on the seeds. The wicking action of the cube delivers and even balance of moisture and air to the seedlings - perfect for new root growth.
Rockwool cubes are wrapped in an opaque plastic foil. This wrap has the same function as the walls of a plastic pot - keeping out light and acting as a barrier for root growth. It also prevents the growth of unsightly, yet harmless, algae. Remove this plastic foil before planting into a hydroponic planter.
Unlike soil, Rockwool's inert properties won't block any nutirents. All elements in the nutrient solution are available to the plant - without the soil getting in the way. Rockwool's inert properties also eliminate fungus and disease which are common problems with young plants.
Grower Tip: Like most growing media, rockwool is shipped dry. There is 0% water in it when you buy it. Before planting, rockwool cubes should be immersed in water (or a rooting solution) until they are saturated and all the rising bubbles are gone.