8 QT Bag of dry fine grade 2 Vermiculite (1.6 pounds)
Vermiculite absorbs and quickly releases moisture, helps maintain a fluffy casing that allows thick mycelium to prosper.
Coco coir is often mixed in a 1:1 ratio with vermiculite to form a suitable mushroom substrate. Vermiculite is an expanded mineral that provides structure to the substrate and retains water, though it is nutritionally inert. The coco-coir vermiculite mix still needs to be properly pasteurized before being inoculated with mushroom grain spawn.