Posted: 01/08/2015 at 16:43
Does the new owner know you're taking those plants? If not, they belong to them not you.
That said, if you water the plants thoroughly the evening before you want to dig them up and let them soak their roots, they will come up more easily and with less damage to the root ball. Place them immediately in pots with fresh compost and keep them out of direct sun but in plenty of light and let them have time to recover and start growing fresh roots. This will also give you time to prepare their new planting sites. If you're pushed for space, wrap their roots in damp newspaper and tie up in a plastic bag till you can get them into pots or the ground in their new home.
Peonies don't mind being moved but are sensitive to planting depth so make sure they are planted at the same depth. Make sure you have dead headed them so they don't waste energy on seeds. The shrubs will do better if you can remove some of the top growth to reduce stress on the roots so shorten or thin the stems.
Keep them watered well so they don't stress between being dug up and getting established again.