I second Frank's comment about the Itohs—they don't seem to be bothered by mildew like herbaceous are but they don't change colors, either, so less interest there. If you like tree peonies Alice Harding is a very short variety that doesn't get leggy, has really pretty foliage even in our arid summer. She needs to be elevated to see the blooms in spring as the blooms droop, she's on the edge of a retaining wall here. Even that didn't help this spring—the blooms that opened were on the side facing away from the yard, bloomed right in to Strawberry Blonde Itoh!