Growing Media Coco Mix works well plugged into pots as a rock wool replacement for growing all kinds of hydroponic crops simply fill small pots with plugs of Coco Mix. The mix contains 70% coconut coir and 30% perlite, with a small amount of clay pebbles, makes a useful soil-free growing medium. With an added plant-based bio-stimulant, which is rich in organic matter and amino acids, it provides an excellent source of micro and macro nutrients.