Gardeners in Asia, Europe and the United States have for centuries been growing peonies for their striking pink, purple, red and white blossoms. The original peony species (Paeonia lactiflora) is rarely found in nurseries and seed catalogs, but the American Peony Society lists more than 8,000 named cultivars. Most peony species grow best in U.S. Department of Agriculture plant hardiness zones 4 through 8, but selected herbaceous species will grow in zones 9.
Numerous cultivars of the garden peony (P. lactiflora), a herbaceous perennial, grow from 20 to 30 inches tall, yielding blossoms 3 to 5 inches wide. Tree peonies, cultivars of P. suffruticosa, are not trees, but rather deciduous woody shrubs that grow from 3 to 6 feet tall, yielding blooms up to 12 inches wide with single or double rows of petals. Itoh peonies are hybrid mixes of garden and tree peonies. Garden peonies typically require a winter chill of more than 400 hours at 40 F or below in order to emerge from dormancy in the spring, but cultivars are available that require just 100 to 200 hours. The seeds and tubers of all species are planted in early autumn.
Peony species are self-fertile. If there are no other peony species nearby, seeds will grow into plants like the original, but if there are other nearby peony species, the seeds might yield hybrids. Hybrid peonies and peony cultivars may not yield seed. If they do, the result is unlikely to be similar to the parent plant. The flowers yield seeds in late summer.
The reason that peony seeds are planted in autumn is that they are doubly dormant. To finish germinating, they need two chilling periods separated by a warm spell. Fresh, ripe seeds planted 1 inch deep in early autumn will produce roots the following spring and a stem and leaves after the second winter. Patience is required to plant peony seeds; they may not germinate for two to three years.
Propagation by Division
To propagate peonies by dividing their tubers, remove the foliage from a clump of tubers and pull it carefully from the ground. Wash the tuberous roots to expose the nodes, sometimes called growth buds or “eyes.” Use a sharp knife to divide the clump into root sections that contain at least three nodes. Plant the tubers of garden and Itoh peonies so that buds are face up and 2 inches below the ground. The buds on tree ponies are located on the stem just above the ground.
- Floridata: Paeonia Lactiflora
- Purdue University: The Peony: State Flower of Indiana
- Royal Horticulture Society: Peony: Tree
- University of California Sonoma County Master Gardeners: Peonies
- University of California King and Tulare County Master Gardeners: Paeonia (Peony)
- Iowa State University Extension: Growing Garden Peonies
- North Carolina State University Extension: Peonies for the Home Landscape
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