A lotus flower form of a tree peony, 'Guardian of the Monastery', Photo credit: TJ Mrazik
Choose the Best Peony for Your Garden
Peonies offer a host of features that let you choose the one or ones best suited to your garden and aesthetic style. Peonies are cold hardy, deciduous perennial shrubs. They grow best in temperate to cold climates with consistent precipitation. And, with the right cultural conditions (e.g. soil and sun), they do well in USDA plant hardiness zones 3-8. They are native only in the Northern hemisphere, throughout much of Europe and Asia. Brown’s peony (Paeonia brownii) is native to the northwestern United States.
Herbaceous peony, P.lactiflora, double flower form
Peonies come in a variety of plant forms and growth habits. Herbaceous peonies are fleshy and die to the ground in winter; buds for new growth are underground. Species of herbaceous peonies that are of particular interest include the following. The common garden peony (P. lactiflora) is the standard herbaceous form found in most home gardens and is available in a variety of flower forms and colors. P. officinalis and P. peregrina are native to Europe and are desired for their red flowers. The woodland peonies (P. japonica and P. obovata) and are best suited for shade gardeners. The distinctive fernleaf peony (P. tenuifolia) is noted for its finely cut, fern-like foliage and crimson red flowers.
An anemone flower form of the herbaceous peony ‘Belleville’
The tree peony (P. suffruticosa) is a multi-stemmed woody shrub. The woody stems are maintained year-round and buds for next year’s growth are located on the stems. Among tree peonies, P. delavayi (red) and P. lutea (yellow) are desired for their unique colors.
An intersectional peony is a hybrid created by crossing a tree peony with an herbaceous peony. Also called an Itoh peony, it is named for Japanese nurseryman Toichi Itoh, who first succeeded in creating this hybrid. Intersectional peonies have strong, short woody stems and large flowers like a tree peony, but die down to the ground in winter like an herbaceous peony,
Allow ample space for your peonies, as these medium-sized shrubs have varied sizes and growing habits. Tree peonies can grow 3 to 7 feet tall, while herbaceous varieties grow 2 to 4 feet, the intersectionals 2 to 2.5 feet, and the woodland species about 1 to 1.5 feet. Most have a spread of least 3 to 5 feet. Plants can be vertical, spreading or compact. Tall herbaceous peonies with large full flowers and long stems require staking to remain upright. Herbaceous peonies with smaller, fewer flowers and short, sturdy stems (e.g. single, Japanese, anemone flower forms) require less support. Tree peonies with healthy, mature stems do not usually need staking.
Springtime Peony Flowering
Home gardeners can create unmatched beauty by smartly blending successive peony blooming with different peony flower forms. Peony flowering occurs for seven to eight weeks, from the end of April until early June (hardiness zones 6 to 7). Flowers typically bloom in this order: woodland peonies, followed by tree peonies and then herbaceous species and ending with intersectional hybrids (Itoh).
Peonies prefer full sun, especially the herbaceous species and intersectional hybrids (Itoh). Tree peonies tolerate full sun to dappled shade, however, their large flowers may last longer in less intense sunshine. The early blooming woodland peony prefers spring sun and summer shade.
Autumn Planting of Peonies
Proper planting or dividing of peony roots is the key to successful flowering. Autumn is the best time to plant peonies, since it coincides with the beginning of the plant’s dormancy. Follow these steps when planting peonies.
- Prepare your soil. Begin with a soil test. Peonies prefer a pH of neutral to slightly alkaline. Peonies need good fertility and require excellent drainage; they do not tolerate wet feet. If the soil is amended properly, peonies can be planted in clay or sandy soil.
- Be familiar with peony root anatomy. Herbaceous peonies have fleshy, thick tuberous main roots with a head-like crown and secondary thin fibrous roots. Sitting on top of the crown are white or pink-colored shoot buds or eyes. Herbaceous peonies are planted bareroot with attached crown and buds (at least three to five). They are usually purchased from a nursery or divided by a home gardener from the roots of a mature plant.
- To divide a mature herbaceous peony, carefully dig up the plant, wash off the soil, and remove any rotted material. Locate the pink to white-colored buds or eyes at the top of the crown. Using a sharp knife, divide the crown into wedges, ensuring that each wedge has at least three to five buds and one to two large main roots to provide food for next year’s new growth.
- When planting herbaceous barefoot peonies (either purchased or divided from a mature plant), dig a generous hole. Place the peony in the hole and cover the top buds or eyes with only one to two inches of soil. Do not plant the buds upside down. If planted too deeply, flowers will not emerge in the spring.
- A bare root tree peony should be planted deeper. Dig a generous hole. If the root is grafted, the graft union should be 4 to 6 inches below the soil surface. If the peony is on its own rootstock, the stem junction should be two inches below the soil surface.
This herbaceous peony root has thick main roots with white to pink-colored shoot buds or eyes on top
Consult the sources below for more information on peony culture and flower forms:
Kamenetsky, Rina, and John Dole. (2012). "Herbaceous Peony (Paeonia): Genetics, Physiology and Cut Flower Production." Floriculture and Ornamental Biotechnology. 6, Special Issue 1 (2012): 62–77.
Halda, Josef J., and J. Waddick. Genus Paeonia. Portland, OR: Timber Press, 2004.
Peony Diseases. Penn State Extension .
The American Peony Society
All photos: credit TJ Mrazik