Our Super Sub is pre-pasteurized and pre-hydrated so you can start growing as soon as you receive it. The substrate is already at the perfect moisture content your gourmet mushrooms need to grow strong through multiple flushes. This 3LB package is the perfect amount of Super Substrate for up to 1QT of colonized spawn; simply break up your colonized spawn and mix in with 1 full package of Super Sub, and your tubs will be ready to set and forget.