I have read that peonies begin to develop feeder roots in the fall and even in winter as long as temps are above 40 degrees. By spring they are ready to send up new growths so the peonies stop developing feeder roots. If you plant peony roots in spring, you will find that the tubers do not develop feeder roots during spring and summer. The growths that occur seem to draw its food from the tubers instead. That is why spring planted peony takes longer to become established.
