I've moved peonies in the spring before but if yours has been there quite a while the root mass can be pretty large. With the larger ones it's almost impossible to get them out without breaking them--no big deal if you're dividing them anyway but you almost certainly won't get blooms this spring if they come out in pieces. If you absolutely have to move them they will most likely survive, though--in my experience it's no harder to transplant in spring as it is in fall, just typically have to wait an entire year for blooms. I did actually get a single bloom last spring from a bareroot from Gilbert Wilde that I planted last April so even blooms aren't impossible same spring as transplanting.
