Peony shrubs (Paeonia suffruiticosa), more commonly known as tree peonies, produce woody branches that don't die back like herbaceous peonies, but drop their leaves in the fall. These long-lived but slow-growing shrubs reach up to 5 feet in height over several decades and can survive for hundreds of years in the same location. Producing larger flowers than garden peonies, the shrubs bloom in spring and their fragrant blossoms appear in shades of pink, white, yellow, orange, purple and red. Both Chinese and Japanese varieties of the tree peony exist, and both require similar care.
Plant peony shrubs during spring or fall, as long as the weather is not exceedingly hot. Choose a planting site that consists of rich, well-drained, moist soil and receives two to four hours of bright sunlight each day.
Dig a hole at the planting site 12 to 18 inches deep and 12 inches wide. Insert the roots of the shrub into the hole and cover with soil. Water thoroughly to bring plenty of moisture into contact with the roots. Space peony shrubs 3 to 4 feet.
Water peony shrubs thoroughly once every 10 to 14 days, allowing the soil to dry out slightly between applications. Soak the soil deeply, applying at least 6 inches of water, to encourage a deep root system. Do not water during winter, when the plant is dormant.
Feed once per year during early spring with a 5-10-10 NPK fertilizer to provide proper nutrition for foliage, flower and root development. Follow the directions provided by the manufacturer for proper application and dosage.
Remove peony shrub flowers whenever possible to help the plant conserve nutrients for flowering the following year. Pinch off each flower near the area where it meets the stem to encourage re-blooming and minimize damage.
Apply a 2- to 3-inch layer of mulch over the soil during mid-fall to insulate the soil during winter. Begin the layer at least 2 inches from the plant's crown to minimize spread of disease. Remove the mulch during spring after all danger of frost has passed.