Hi, you've put yourself in a little bit of trouble - your climate's quite cold, but you can't leave those trees inside either. I suggest you sink the plants into training boxes (large wooden ones) full of mulch, with a couple of inches above ground (though not touching the trunks) and keep them in the coop. They should be ok, but once the soil freezes (and presumably their leaves are gone) don't water, though putting handfuls of snow on top for 'natural' watering if or when it ever warms up enough to thaw it, is a good idea.