Sarah, Have the plants in your greenhouse been blooming or are you unsatisfied with the quality of flowering? I find I can get Cyclamen graecum to flower and set some seed here on the southwest coast of Oregon if I leave them in the poly house through the summer, where I think intensity of heat counts as much as intensity of light. I'm just south of the 45th parallel. If they aren't flowering at all or poorly, I'd definitely supplement the light, although surely more lengthly exposure to light in the summer should compensate for less intensity of light to some degree the further north you live. Can someone comment on this? Thanks, Robin Hansen Nursery robin@hansennursery.com