I've never seen one of these before. We bought two about 3 years ago because we liked the picture on the label. They didn't seem to like where Chris planted them and the one Chris chose actually died. He put my one in a pot and it's looking much healthier. It's even produced a flower (just the one!).
SO pretty. Sounds like when I try to grow anything..... I don't have a green thumb. However, from past photos you do a whole lot better..... Love your yard photos.
I've seen tree peonies at the garden centers, but have never tried to grow one because I wasn't certain how easy they are to grow. This flower is beautiful, though, I can certainly see why you bought a couple of the plants.