Description Grodan granulate retains about 20 times its own weight in water. Grodan rockwool granulate is best suited to recirculating systems. It has a very high water holding capacity which means that it does not need to be watered often. Rockwool has a higher pH and must be adjusted for best results. Grodan Rockwool is a sterile medium specifically designed for the horticultural industry, made out of specific basalt stones. Grodan granulated rockwool can be mixed with other growing mediums to achieve more or less water retention. Ideal for cloning your favourite plants, or geminating your favourite seeds. Care should be taken when handling rockwool by wearing gloves and a mask. The rockwool fibres can cause irritation to the skin, and if breathed in they can also irritate the lung.
