Peonies are resilient plants that have been discovered in old gardens decades after their keepers had abandoned them. The crown from which the peony grows, however, is not quite as rugged as the plant that rises from it might appear.
Peony plants grow from fleshy roots called rhizomes. The rhizome stores food for the next year’s plants. Embryonic shoots spend the winter in little reddish-colored "buds" atop the rhizome; large "feeder roots" hang underneath.
Puncture wounds from garden tools and support stakes can damage the rhizome, leaving it vulnerable to fungal or viral diseases. Peonies may bud the following spring if enough of the crown and feeder roots are left intact. Eventually, disease will kill the plant.
Old and overgrown plants and damaged crowns can be trimmed to make new plants but decaying or damaged tissue must be removed. Each new division needs at least three to five buds and two feeder roots to survive.