Last year, we had temps up to 109 in the shade with the wind blowing. My regular peonies which were in full sun would wilt in the afternoon. I put down about 3 inches of cedar bark mulch with a strip of about a foot left open down the middle of the short bed so they would have breathing room. After soaking the bed with water a couple of times, they did not wilt. Most of the time, during hot summertime, I try to water peonies every 4 or 5 days just to give them moisture to spread and grow new roots.
