Grodan Rockwool - 4x4x2.5in. Cubes, 6 pack w/holes

Rockwool is an inorganic and sterile growing medium made from spun molten rock. A superior medium for rooting cuttings, rockwool provides 20% air space when saturated, and does not contain nutrients. It is recommended that rockwool be conditioned by soaking for eight hours in a pH 5.0-5.5 and then rinsing with pH 7.0 water. Water daily.