Out-Grow only uses 100% certified organic popcorn grains for our popcorn based mushroom substrate grow bags. Popcorn mushroom substrate makes a fantastic spawn and will support any gourmet mushroom strain. Popcorn has a great consistency and provides solid inoculation points when spawned to a bulk substrate. Out-Grow fully hydrates and sterilizes the popcorn substrate in a mushroom grow bag so its ready to use immediately. There is a bit more time and labor that goes into making popcorn mushroom substrate then rye or wild bird seed. Each bag weighs one pound and is equal to 1 quart in volume.Recommended 2 -4 cc of your gourmet mushroom spore solution per one pound bag. You can also use these bags for grain to grain transfers to expand your mycelium.