Most astilbes are hardy to Zone 3. Astilbes do best in moist, well-drained soil, and prefer partial shade. A final treat for those of us who have some shade in our yard is the beautiful hellebore family. Among the earliest of the early-bloomers, these flowers most often come in shades of pink, white, or red, although new colors are currently being bred by fanciers. The leathery, divided foliage is also attractive when the plants aren't in bloom.
Hellebores demand moist conditions and prefer partial shade.