I just completed my first phonebook grow, also inspired by this post. Thanks.
One problem I am having is fresh air exchange. As a result, most of my mushrooms are coming out very stemmy. I've found that the best conditions for the season are to keep them with the furnace, inside of a clear garbage bag that is propped up with some holes in it. I am misting it a few times a day. The problem is if I leave the bag open to encourage more air exchange everything dries out; if I close it more I get good fruiting but stemmy mushrooms.
I would like to avoid using perlite, simply to avoiding another input into the system. I am about to start fruiting another phonebook I innoculated, any suggestions to fix this problem would be great!