Answer: There's something very special about "living heirlooms" - they're rooted in our memories as well as the earth! I suggest that you make it part of the terms of sale of the property that you can return at a later date to divide/remove the iris and peonies. Neither will do well out of the ground for very long, especially peonies. Iris are often stimulated to bloom after division and transplant, but peonies are set back by transplant, and may refuse to bloom for several years after the fact.
If you can't work this out with the buyers, then prepare a nursery bed in your own yard or garden where you can plant them temporarily. Another option is to donate them to a botanical garden or other heritage garden, again with the condition that you can have divisions later on. I'm not sure how the peonies will take this kind of repeated transplant, though. I hope you can work it out with the new owners! Best of luck!
Q&A Library Searching Tips