No advice, as I'm kind of in the same "boat", having bought a 'Cinnamon Snow' at a grocery store. I say "kind of" because I don't have a garage or an enclosed porch or an unheated basement.

I'll be watching. Hope you get some help.
Molie

Is the plant in leaf and or bud? If so it may well have come from a greenhouse in which case it will definitely need hardening off and planting at a more gentle time. I've never experienced that kind of cold nor bought a Hellebore so I can't really help much further.

Mine are all pass alongs or seedlings and are beginning to show some buds just now.

Thanks 'floral'. The plant has beautiful flowers and buds. I do now plan to keep it in the garage until more moderate weather. Today it is in the 50s. That's the Rocky Mountains for you!

It will still need a lot of light, though. Will it get it in your garage? You could stand it outside in the day time to start toughening it up a bit. I have just looked up Jacob and see it is a Helleborus niger cultivar, so a bit more finicky that the H orientalis hybrids I grow. I suggest you do a little research as H niger can prove a challenge. The link suggests Jacob may be dubiously hardy in z5 and would not normally be in flower there in January.

Here is a link that might be useful: Jacob