Perlite

Perlite

When growing mushrooms, perlite is used mainly to maintain a very high level of humidity within a terrarium/grow chamber. It provides aeration and optimum moisture retention for superior mushroom growth. Other benefits of horticultural perlite are its neutral pH and the fact that it is sterile and weed-free.

If you’re making a DIY kit with a five-gallon bucket and a humidity dome, perlite is the easiest and most effective way to achieve high amounts of humidity.