While the cold will ruin the blooms... 7° did for mine... There are hellebore nurseries in Canada... zone 8 isn't going to throw more cold at those plants than they can handle. At my house... I grow them in the dry sand, and when we had that extended drought... they got by on zero extra water.
I have some planted in full sun... they do fine there.
I have seen them suffer in water-logged clay... so... too much water... could be problematic.
