How mild was your winter? If they're planted deep enough for a typical zone 5 winter a mild one might deter bud formation but it'd have to be REALLY mild. How many years have yours been in place?

Bloom has been good this year--in general (there are always a few exceptions). However, since very few days have been free of rain, blooms got battered. Thus, not a good year. But hot sun can be just as bad.

My two Itohs have been doing great--not only will one be blooming for the first time--but it has half a dozen buds on long stems! High Noon tree peony is doing about as well as it normally does--it is a big bushy plant. Krinkled White herbaceous is about the same as normal. Winter was pretty mild except for one day in which it got down to -11 and knocked most of my roses down to a couple inches--they are shorter but more bushy--I had to make a lot of the hardware cloth rabbit protection hoops bigger.

Have they been getting enough water? You said you had little snowfall--which may mean you went into Spring with the ground much drier than normal.

I agree with Zack. Maybe your peonies did not receive enough moisture this year due to the lack of snow fall? My peony season has been ok. I have a lot of bud blast, deformed flowers, and a full mature bush with only 4-5 stems of flowers with all the other buds blasted. Of the ones that do survive and open, they are all very nice looking. I don't know whether the bud blast was a result of the freeze that happened while the peonies buds were forming because we had two nights dipping down in the low 20's in early spring.

Hmmmmmm.....water........I suppose that could be it. I had been giving my entire cottage garden supplemental water this spring, but I could imagine that they got a lot less than normal overall.

Figures, what few tree peony flowers ready to pop are now blooming and wilting immediately in the hot weather! I was hoping for it to remain cool for a while! Next year!!