Doris I have divided mine in spring and fall. Though I was told after the fact that you weren't supposed to divide them at all!!!! They did just fine and didn't seem to mind at all. I have since learned that it is sort of plant particulars as to which ones you can divide. Below is a link with a table that gives the info on which ones divide well.

Hope that helps
Angie

Here is a link that might be useful: Hellebore Division

Good information! Thanks for the link!