Summer Care for Peonies
After a peony has bloomed in the spring, it still has a critical job to do. All summer it needs to photosynthesize and store energy for next year's bloom. For us the show may be over, but let's take a few minutes now to set the plant up for a good summer.
In my climate, the hot summer is a bit of a stress for peonies. I try to do what I can to help them weather it happily:
Trim: After any blooms have faded, unless you're trying to get seeds, clip off the spent flowerheads above the first set of leaves. Also trim any stems that have been damaged. Cut 1/2" or so below any damage, into healthy tissue. If there's been any issue with disease, remove the trimmings from the garden altogether.
Mulch: If you've decided to mulch, and haven't done so earlier in the season, do so now. Mulch will keep the roots cooler during the summer than bare soil.
Water: Peonies are famous for being drought tolerant. Still, like any plant, they appreciate regular water. My rule of thumb is, if there hasn't been an inch of rain in the last two weeks, water peony plants deeply.
Other than this, your peony plant won't need much from you in the summer. If it's had a beautiful, flower-covered spring, maybe a thank you would be nice.