baking soda and water..

or a bunch of other ways ... you might try the GW search function ....

and make sure you are not wetting the plants late in the evening.. dry plants.. in full sun.. should not get mildew ...

ken

I'm a big fan of Neem oil. I've never seen mildew on my coneflowers, but our winter was so mild this year, I've been seeing it elsewhere for the last month already. Neem oil is primarily used as an insecticide/miticide, but it also has fungicidal properties. It's pretty much the only garden "chemical" I use because it's so effective against a broad spectrum of common garden issues-- plus it's organic.

You can find pre-mixed bottles of neem oil spray at just about any garden center, but they're a bit pricey. I use so much of it, I buy the pure oil and mix it myself-- 2Tbsp oil with 1Tbsp of old-school Dawn dish liquid in a one gallon pump sprayer. I say try a bottle of pre-mix, and if it works for you look into buying some pure oil. I buy it by the gallon from a website called organeem.com. One gallon usually lasts me at least a season, but it's the best price+shipping cost I could find.