Quote Originally Posted by DVirginiana View Post
If you freeze it for several weeks, yes. I'd recommend baking (for substrate... maybe not sphagnum moss. Seems like that might burn a bit to easily).

EDIT: I'm assuming you're using cypress mulch, eco-earth ect. or something similar to those for substrate.
Isn't overnight enough? Current nighttime temp is around -10C or 14F.

I leave Coco Husk bricks outside and then when time to use, pour boiling water over it.