Sorry - I can't help you with your question but you might like to try it on the Hellebores Forum or even the Perennials Forum as they get more traffic than this one, especially the Perennials one.

Hi there-
I grow lenten roses in shade cast by my neighbors hideous canary island pines and my tallow tree. I started slow with one-now have 3. Mine get hardly any sun, but its hot here (100+) all summer, little humidity.
They are doing great-my only complaint is that the flowers nod forward so its hard to see them.
Hope this helps.