Recovering mildewed peonies
I moved into a house with 3 peonies already in the narrow urban backyard. The first year, only one bloomed a little, and they died off to mildew toward the end of the season. Last year they didn't bloom at all, and were killed quickly and severely by powdery mildew. I cut off the dead foliage and did not compost it. Mildew also affected the zinnias, but not as severely. The beds are narrow with lots of sir circulation and full sun.
Will these plants recover? What can I do to prevent the mildew problem? I am not keen on chemicals.
(Between the mildew, the black spot that came with the roses, the Canadian Thistle invasion, and the squash vine borers that kill all my squash, this new yard has been tough!)