Peonies are a garden favorite. The flowers appear in early summer. They may be very large, double peonies resembling massive balls of tissue paper in shades of pink, red, purple and white, while others may be single peonies atop tall, thin stems with bright-yellow centers and vibrant petals. Peonies are low maintenance. To encourage as many blooms as possible, follow some basic rules for end-of-season care. Under the right conditions, peonies may bloom for 100 years or more.
Cut back the foliage to about 2 inches above the ground and lift the plant out of the ground with a large gardening fork. Knock loose any clumps of dirt and then rinse the roots to remove the rest of the dirt so you can see the eyes. With a sharp, clean knife, divide the root clump into smaller clumps, each with three to five eyes. Replace the original plant in its hole, watering it in to remove air bubbles. Division plants bloom in two seasons.
Apply a layer of compost 2 inches deep around the plant, keeping it away from the base. Don’t cover the entire plant if you’ve already pruned it back for the winter. Avoid nitrogen fertilizers, as they encourage late-season foliage growth that cold weather kills.
Prune peonies hard in the fall once the foliage turns brown. Use clean, sharp pruning shears. Sterilize the shears in between plants by dipping them in a 10 percent bleach solution. Prune all the foliage, so the plant has just 2 inches of stems protruding from the soil. Burn the foliage, especially if any of the plants suffered from botrytis blight during the season. Most backyard compost piles are not hot enough to kill the virus.
Fall is the best time to put in new plants. The cold treatment they receive in winter is necessary for their success. Prepare the site two to four weeks before planting, as the University of Nebraska-Lincoln advises. Plant peonies in their own space where they won’t compete with shrubs or trees. Loosen the soil up to 24 inches deep but no less than 18 inches deep. Plant each peony in an18-by-18 inch hole. Toss in a handful or two of compost and water to settle the soil before setting the tubers. Set tubers so the eyes are no more than an inch below the surface. Mulch the new plants with straw after the ground freezes.