Two summers ago I purchased 3 gorgeous peony plants from Sunnyside Gardens. This year they are covered with powdery mildew. What is the best course of action to treat the plant? I’d hate to lose them! Thank you for your help.
The mildew on your peony plants is ugly, but rest assured, isn’t going to do too much damage. I would recommend spraying with a fungicide and fertilizing with a liquid fertilizer. By fall you will want to cut back the peonies and discard the leaves away from your compost pile as they are covered in spores (a spray of fungicide now will help to kill those spores, but some may linger). Applying fertilizer now will help ensure the damaged, stressed leaves can produce enough energy to be strong next season. Odds are good that your plants will recover nicely as they come up fresh next season.