After I mentioned that Lycoris did poorly for me in western Oregon, Val in inland northern California asked: Jane, would you please write about why Lycoris does badly in the far west? I had thought it was just Lycoris sprengeri that we couldn’t grow and that it > was my fault that the others didn’t. > Years ago, I was talking with author and nursery grower Sean Hogan and mentioned that I couldn't succeed with some plants from Japan and the eastern USA. I wondered if there was some factor they shared to which the US Pacific coast region was inhospitable. His opinion was that the different levels of atmospheric humidity in summer might be the cause. In summer-dry regions, low humidity results in pronounced temperature drops at night (commonly at least 20 degrees Fahrenheit, sometimes more), whereas in moist-summer regions at low elevation, night cooling is not to be so sharp. The cold nights might trigger dormancy and interrupt the typical annual growth and flowering cycles of plants. It's well known that some cultivars of daylily (Hemerocallis) will not flower well, or at all, in the Pacific Northwest, but flower well east of the Rocky Mountains. Temperature drop might be even sharper where Val lives than it is here in a suburb of Portland, Oregon, since her area is both drier and at higher elevation than mine. When I go to the east or southeast USA in summer, I feel as if I'd stepped into a steam bath. This doesn't occur with all plants from humid-summer regions. Japanese lilies do well here, as do a number of East Asian genera in the lily family (broadly speaking; is it Liliales now?). Perhaps it's more common in summer-flowering plants than in spring-flowering ones? On the other hand, Kirengeshoma (Hydrangeaceae) is flowering well in my garden at the moment, right on schedule. It can even be affected by microclimate: I notice that only a quarter-mile from here East Asian plants and eastern American trilliums flourish much more than in my garden, which is on a ridge, and that garden is in a moist, sheltered site that slopes down to a permanent stream, presumably having more humidity at all times. On the other hand, some plants do well here but are difficult in the east because they succumb to diseases promoted by summer moisture (e.g., Dianthus). "Hardiness" and "zone ratings" are not a dependable guide to how well a plant will grow and, especially, flower in a given place. Factors that aren't readily available as data, such as seasonal humidity and rainfall cycles, have to be considered too. Jane McGary, Portland, Oregon, USA _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/…