Mary Sue asked >How much winter rainfall can these [aril] irises tolerate? I also live in a region with heavy and prolonged winter rains, often lasting into June, and my experience is that Oncocyclus irises cannot tolerate this climate even under the protection of the bulb frame. They generally produce some foliage in late fall and this is very susceptible to fungus and/or bacterial infection, which saps the plant's strength and eventually kills it. I think you could grow them with a careful program of spraying, but I don't want to go to that length. The mere moisture in the atmosphere seems to promote these infections, even if no rain actually hits them. In contrast, hybrids between the Oncocyclus and Regelia sections (known as "Regeliocyclus" or "Oncogelia" hybrids) do extremely well in the bulb frame because they don't produce leaves until early spring. Many of them have the same spectacular marking and coloration as Onco irises. I haven't tried them in the open garden, however. Jane McGary Northwestern Oregon, USA