I'm in 4b also but usually with a passable snow cover. Some of the peony specialists (Solaris for example) will rate bud hardiness and whether they put up new shoots readily but when considering particular cultivars it is often quite variable. I find t.p. Yae Zakura keeps most of its stem buds and of course there is always High Noon - if it loses stem buds by Spring you'll almost always have flowers in September
This is an Aug 28 rebloom
