Why do my peonies get a mildew look after blooming? Friends of mine say their peony plants keep looking good until frost. What do I do to eliminate this problem next year?
Cooler nighttime temperatures and rain have contributed to powdery mildew being a problem on many plants, including peonies and monarda. This late in the season I would just cut off the foliage and cleanup any leaf litter. Should it happen earlier in the season, use a fungicide like Daconil to stop its spread.
Have a great fall gardening season.