Answer: The best time to transplant your peonies is late summer/early fall. You can begin once the weather cools down--mid September should be fine. Iris, too, can be transplanted at this time. I'd wait until spring to transplant the sedum, so you don't disturb it during its fall flowering time. You might want to mulch the peonies (after the ground freezes) with a layer of hay, to help insulate them during their first winter in their new spot.
Daffodils should be planted in early fall--September or early October. Wait until mid-fall to plant the tulips--they are prone to sprouting in the fall if planted too early.
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