In 2010 I bought a Helleborus niger from the late Seneca Hill Perennials that owner Ellen Hornig said bloomed at Thanksgiving in her Zone 5 garden. It's done the same thing in my garden, though not consistently. I have this Hellebore planted on either side of a path. One bloomed beautifully last fall while the other set buds but they never made it to blooming stage. Hornig noted in her catalog that sometimes the plants bloom in spring as well. I would say "here's the proof" but I am not sure if we're in winter or spring!