posted 6 years ago
Exposing the entire colonized mushroom block surface will allow the block to dry very rapidly, which isn't good for oysters in particular. Keeping the bag on allows a protective layer of humidity right where primordia should be forming. Even at a high humidity, air moving through a fruiting chamber can have a drying effect (especially if dry air is vented in and then humidified after entering). Also, if you do expose a large surface area, oyster blocks can grow a lot of tiny, long mushrooms in the shape of a wig or beard, as opposed to just a few nice clusters.