Congrats on catching the peony bug. I got bitten about 5 years ago. It can be intoxicating. Here in Zone 7, generally, the tree peonies bloom first, followed by the itohs and herbaceous. But each type has early, mid, and late bloomers so there can be quite a bit of overlap. I have found my itohs to be easier to care for, grow, and are show stoppers because there is no drooping of the blooms. The tree peony blooms are beautiful but the plant can be more fickle, take longer to bloom and develop. The itohs behave much more like herbaceous peonies. I don't look at them in comparison. Each has their own merits. Just some of my thoughts and experiences.
