Mine started blooming in early March and is still blooming. This is its second or third year blooming. Mine is a hybrid, I think. My second one did not bloom yet, maybe next spring.

There are many European legends surrounding the Christmas-rose (H. niger). One of them is that a poor young shepherdess named Madelon started to cry because she didn't have a gift for baby Jesus and she shed tears in the snow near the stable in Bethlehem. An angel came down and showed the girl flowers blooming where her tears had fallen, so she picked them and gave them to the baby Jesus. (Historians have shown that the plant is not native to the Holy Land, however.)

To your point however, H.niger can flower at Christmas in a mild zone8-9 climate. Probably when the temperature reaches 8-10 degrees centigrade(40-45 F) for 10 days or so. This has not been scientifically measured by me, simply observation on plants in the garden, the one in the most sheltered spot always flowers first, and varies from year to year according to the weather we have had.

So I guess in Zone 5, you'll be seeing it in March??

Cheers Greenmanplants