I have about 70 peony cultivars (multiple plants of some), and they are planted in different parts of my very large farm yard. Most are in full sun and I have noticed that the few that only have half-day sun don't bloom quite as well as others. Pips started coming up on Mar. 20, and 2/3 were up by Apr. 5. The very last one to emerge (today) is 'Romantic Lace'... I had about given up on it, so I was thrilled to see it. Now most have buds, and the first 2 bloomed on May 8. Both are species: anomala veitchii and mlokosewitschii.
I tried and tried to get a good photo of the whole clump of mloko. (overcast day so I don't think too much light) and from every angle the petals looked white. But the color is perfect on the close-up of a single bloom! I remember having trouble getting true color on Bartzella last year too.
Anyway, I am really looking forward to the next few weeks as more and more peonies start to bloom. Some buds are starting to show color... this is such an exciting time in the garden! And the martagon lilies are about to start blooming also! And then the daylilies...