Watering Semps Durring Winter

Hi all was wondering since i havent kept semps in the GHs durring winter months befour, i would like to this winter if i can and was wondering how do i water them durring these COLD FROZEN months? There pots are not that big but i surely dont want them sitting in moist soil freezing and not drying out, how do you all keep your semps in GHs durring winter months?? Do you have a humidity in the GH durring the winter? Dont know if your temps get as bad as ours but we can at times get temps as low as -20 to -35 below zero.. These are all my newely aquierd young semp collection dont know if they can handle this right away or are the still destressing from shipping and repotting?? They are all doing well.. All my other semps are outside in ground been there and are use to the bad winters we get.

Any advice is greatly apreciated...

when frozen, I don't water. But they are better off under snow when they don't dehydrate so much. I regularly get temperatures like yours, no problem for most (I didn't try with S. atlanticum, as it is reported to be less hardy in winter). I have them outdoors, in full sun. I think that greenhouse-grown semps have a very hard time adapting to the rough outdoors climate, but once they are adapted, they do much better in the open. These are mountain plants, used to strong sunlight and extreme fluctuations in temperature.