Our best-selling Boomr Bag is a sterile manure-based bulk mushroom substrate formulated by mycologists to increase the yield of your grow. Over several years, the recipe has been perfected for dung-loving mushroom species and is widely-trusted by mushroom growers. Use Boomr Bag in monotubs, filter bags, and outdoor beds. Or, grow mushrooms from the bag or in a tray using a humidity-controlled grow room or Martha setup.