Here in NH, zone 4b, once the snow starts, usually in November, all bets are off as far as flowering plants. Ornamental grasses, rose hips, textured bark, garden structures are suddenly in sharper focus covered in new-fallen snow, or twinkling in sunlight with frozen water droplets. I would love to see how others pull this off. It is not easy to plan ahead, but Mother Nature usually gives you some starting places.
lol sorry. my violas are still going and i had an iris bloom in nov. up until last week my roses were still trying to grow.. we are probably the cut off for winter flowers. maybe 5b. the crocus are already coming up and will bloom when we have a warm spell. the daffodils are already growing. we are pretty mild until mid jan and mid feb then we get teens and 20s. sometimes.