Yes, I think they do. And my attic, with its sunny window, may be the perfect spot for wintering dendrobiums. Hmmmm.... I saw a Den. chrysotoxum at my orchid society meeting yesterday that totally plucked my heartstrings--I've seen photos of it and wanted it for 30 years, this was the first time I saw it in real life---I really need to figure out how to grow dendrobiums....