Answer: As it turns out, powdery mildew is unlike other fungal diseases in that frequent, hard rain actually inhibits the establishment of the disease by washing the spores from plant leaves. Good air circulation in a shady area is actually ideal for powdery mildew, while full inhibits its growth. There are ornamentals less susceptible to powdery mildew that would do well in this spot, so long as they receive some sun during spring days. Peonies are not commonly susceptible to powdery mildew, but they do need a rich, well drained, humusy soil to do really well. Cape Figwort (Phygelius capensis) is a tall-growing perennial (6') that has bold, red, tubular blooms. It does well in hot sun and dry soil, and has a long flowering season. I'm truly not sure if this is resistant to powdery mildew, but it is not on my list of succeptible plants. A source for Cape Figwort is Heronswood Nursery Ltd., 7530 288th NE, Kingston, WA 98631; ph#360-342-4856. They should be able to tell you more about it. Another vine is silver lacevine (Polygonumaubertii) available from Lamb Nurseries, Rt 1, box 460B, Long Beach, WA 98631; ph#360-642-4856.
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