[Thamnophis]

I agree with you, Ssssnakeluvr, that the substrate must not be all damp.
I do it like this.
MY hibernationboxes are rather big. One half I keep a bit most and the other half dry. So they can choose where they want to be.
Personally I start end oktober/begin november and finish end februar/begin March.
But this is also depending on the species you keep.