In the dark, in the garage should be ok, while temps are this low, but once the temperature begins to rise, even just a few degrees, they will start to grow chits and without light these will get long and brittle, if left too long.
Ideally they need to be cold, but not frozen, and in the light so that when they do start to grow the chits will be short
The problem is they might freeze in the shed, while it is this cold - unless you religiously remember to cover them every night and whenever the days are freezing.
I bet few of us manage ideal conditions, so if the chits get too long in the garage, rub the longest off and they will regrow
