peony in zone 5

I always default to cutting non-woody perennials after they're frosted real hard. Actually, I just leave 'em alone until spring, then I clean them up. Just wait till the new points are coming up, that's a sign that you really should tidy up a bit...

I cut mine down about 2 monthes after they bloom. I've had them for 12yrs. Sue in Mi. (Zone 5)

I would clean them up now. The one problem I have with peonies (a form of mold/mildew???) is kept under control by cleaning away the dead leaves as early as you can ... You also avold risk of damage to the delicate new growth. DK

Remove peony foliage to 1/4" below soil surface and discard. You thus remove most of the disease spores for next year. There is no need to wait until frost as most of the nutrients are allready in the tubers and there is little photosynthesis occurring in these short dim days of autumn.