Emma, do not worry a bit about it! Easy come, easy go. :-) I dug peonies in late March after they were fully up last year to move to my new house and I gave a division away to a coworker. Both the transplants and the division were fine, but I could tell the smallest one was the one I'd divided, as it didn't grow as large as the others that summer. In my experience, peonies take about three years to feel at home enough to bloom in a new spot, and I wouldn't want you to chance anything particularly precious or special. For Fling plants I've brought before, I've either dug the weekend before or the morning of. It was a mad dash for the morning of, so will be doing my digging tomorrow! My tomatoes are small, and I've just begun hardening off (although I have had a fan on them to strenghthen their stems to our wind) and hope I'll have some ready to bring next weekend.

Early fall is the best time. If you will divide it now, it could be too stressful for the plant - it might loose the foliage which is the important source for feeding your Peony during the growing season.

It may depend on what your aunt will let you do, as well as your willingness to do the heavy lifting. This is not the best time for this project. Her peonies are probably in bloom. Maybe you are going to visit in the fall. In the fall I would dig the whole plant up using care to not break off any more of the tuberous roots in the digging. With a strong stream of water wash off all the soil. In the fall you will be able to see the buds for next years growth and with a sharp knife cut up the roots leaving 3 to 5 five buds on each piece. There will be some tuberous roots where no buds are visible. Plant them in pots anyway because the energy stored in the fleshy roots will often cause advantageous or dormant buds to grow. From one old peony I can usually get up to 10 viable plants. If you are visiting your aunt now I would be content to cut a division from the plant in the ground from the edge of the root mass and not disturb the rest of the plant. Al

Early spring, or Fall. I've always divided in Fall before the first freeze, although this year that may be hard to predict. If you miss getting it done this fall, you can do it early spring. Have you ever divided them before? If not, make sure to leave the eyes above dirt level a little bit. Emma