Questions about hellebores

So, Lynda, they really do bloom in the snow, unlike snowdrops or crocus, which wait until March for me? How important is snow cover? If you have good snow cover, the soil doesn’t freeze and I guess I can see how they might bloom. But what about if the ground freezes solid and there’s no snow cover and it’s way below zero (F)? Do they just come up later, or does it kill them? Are yours in a sheltered spot?