13.6Kg Premium Floc - Rockwool Growing Medium Plant Fruit Flower GrowoolGrowool has a unique combination of properties which make it an excellent growing medium. These properties need to be considered if the material is to be used to its maximum effectiveness. Properties: Very light when dry, with a void space of 95% Natural rock and is not biodegradable Sterile when packed Inorganic and contains no nutrients Very low cation exchange capacity, so will not bind nutrients A slight pH rise on initial wetting, after which it