03 February 2016 What is Bulk Substrate? Written by Hannah Glückspilz Bulk Substrate is a mildly nutritious material of greater volume that is used for mass mushroom cultivation. Bulk substrates are pasteurized and then usually mixed with a pre-colonized spawn which is made with whole grains such as rye berries or... Read More Mycopedia bulk substrate, coir, Compost, rye berry, worm castings 8 Comments