Hi Jasmin - As I have been digging so many peonies lately, tree and herbaceous, I can reliably say that those that are still growing/have good green leaves still have many small white feeder roots while those whose foliage has pretty much shut down for the winter no longer have visible white feeder roots. I would say this points to a MUCH earlier initiation of feeder roots than you suspect and a decline as the temperatures decrease. Logic has it that when they have finished blooming they will start to 'reload' for next year's blooms.
