Answer: It's been my experience that perennials divided in the early spring fare better than those divided and replanted in the fall. Digging and dividing can be stressful on a plant so it takes a few weeks for them to recover, especially in the colder weather when growth naturally slows. In addition to that, the roots will need another 4-6 weeks to become fully established in the garden. If you dig and replant in the fall, the plants won't completely establish until next spring. I'd wait until spring when they've finished resting for the winter and are ready to grow. Dig and divide them then and they will barely miss a beat.
Best wishes with your garden!
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