Peonies

Prepared by Karen Russ, HGIC Horticulture Specialist, and Bob Polomski Extension Consumer Horticulturist, Clemson University. (New 04/99. Images added 05/09.)

HGIC 1170

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The large showy, flowers of peonies are produced in mid-to late spring. Many colors and flower forms are available. Because winter chilling is required for dormancy, peonies often do not perform well in the lower South. Early blooming and single or Japanese cultivars generally perform better in South Carolina than other types.

'Coral Charm' peony
Wikimedia Commons, Poupon I'quourouce, Creative Commons License 2.5

Height/Spread

Most herbaceous peonies grow 2 to 3 feet tall in our area with a 3-to 4-foot spread when mature. Some cultivars and species will grow a foot taller or lower. Tree peonies (which are actually a shrub) grow to about 4 to 5 feet under normal conditions.

Growth Rate

Peonies are long-lived, but slow-growing at first. Garden peonies will usually begin blooming within three years after planting. Tree peonies will begin blooming at about the same time, but will increase slowly in size and bloom quantity. They can live for up to a hundred years.

Ornamental Features

Peonies are grown for their large, showy and fragrant flowers. Most peonies have very attractive foliage that makes them a useful addition to the landscape all season.

Landscape Use

Peonies are used as specimens in borders and herbaceous hedges and are excellent cut flowers.

Herbaceous peonies need at least six hours of full sun a day for good bloom. Afternoon shade will protect flowers from fading too quickly in hot areas. Tree peonies should always have dappled or afternoon shade since the large, silky petals are damaged by excess sun. Well-drained, loamy soil is best for good growth of peonies. Good drainage is vital to avoid root rot and fungal diseases. If your soil is heavy clay, amend it with compost, finely ground pine bark or well-rotted manure to improve drainage and organic matter content.

Well-drained, loamy soil is best for good growth of peonies. Good drainage is vital to avoid root rot and fungal diseases. If your soil is heavy clay, amend it with compost, finely ground pine bark or well-rotted manure to improve drainage and organic matter content.

Peonies prefer a pH of 6.5 to 7.0. You may need to add lime to your soil to raise the pH for best growth of peonies. Peonies are long-lived in the garden and are worth extra trouble at the time of planting, since they may stay in the same spot for many years.

Fall planting is best. Dig a hole 12 to 18 inches deep and 12 inches wide. Replace part of the soil in the form of a cone and spread the roots over it. Set the roots so that the tip of the eyes (swollen pink or reddish buds) will be no deeper than 1 inch below the surface of the soil. Most failures to bloom are caused by deep planting.

Tree peonies should also be planted in fall. The graft union should be an inch below ground level. Mound extra soil up around them for the first winter.

Firm the soil in well around the roots, eliminating air pockets. Water thoroughly.

Divisions with three to five eyes will reach maturity sooner than smaller divisions. If one or two eye divisions are used it may be several years before the plant flowers.

Water peonies thoroughly and deeply once every 10 to 14 days. Deep watering will encourage deep rooting. Once established, peonies are very drought-resistant.

Apply a low nitrogen complete fertilizer such as 5-10-5 or 5-10-10 at the rate of two to three pounds per 100 square feet in the spring when the stems are about 2 or 3 inches high. Well-rotted manure may be used to improve the soil if it is applied to the soil surface in a 1-to 2-inch layer. Never let fertilizer or manure touch the stems of the plant.

When you work around the plants in the early spring, be careful of the tender emerging shoots. They will usually be dark red.

Remove seed heads after flowering is finished to allow the plant to store more energy for next year's bloom.

In the fall, after frost, cut back the dead stems of herbaceous peonies down to the soil surface. This is very important if you have had any disease problems. Discard the stems. They should not be used in the compost pile.

NEVER cut back tree peonies. They are shrubs and will not grow back if cut down.

Peonies may be left undisturbed for many years. If you want to divide or move your peonies, do so in late September or October. Carefully lift the clump and wash away the soil to expose the eyes. Using a clean, sharp tool, divide the clump into sections, each with three to five eyes and good roots. Replant immediately.

Most peonies need support to prevent the stems from flopping under the weight of their flowers. Commercial hoops are available for this purpose. You can also use a ring of three or four stakes with loops of tape or plant ties to attach the plants to the stakes for support.

When you cut peonies for the house, pick the flowers in the soft bud stage. They should feel like soft marshmallows. Leave at least 3 leaves per stem on the plant. Recut the stems under warm water and strip off any leaves that would contact water in the vase. The flowers should open within a day of being placed in a vase.

Problems

Peonies have few pests or diseases. The most frequently occurring problems are the fungal diseases Botrytis blight and leaf blotch.

Peony leaf blotch
Jody Fetzer, New York Botanical Garden, www.insectimages.org

To help control diseases, cut off all peony plants level with the ground in the fall. Do not add the old tops to your compost pile. Avoid overhead irrigation.

The only insect pests of any consequence on peonies are scales and Japanese beetles.

Ants are attracted to peonies because of the sweet sap the flower buds secrete. It is a myth that ants are necessary to permit peonies to bloom.

A common problem of peonies is the failure to bloom. It may be the result of planting too deeply, immature plants, excess nitrogen, inadequate sunlight, overcrowding, nutrient deficiency, insect or disease problems, competition from roots of nearby plants or late freezes. Some cultivars will fail to bloom in zones 8 and 9 because they lack sufficient winter chilling.

Cultivars

There is a vast array of peony colors and forms to choose from. Most gardeners are familiar with the large, double-flowered peonies. Garden peonies are also available in single-flowered, semi-double, Japanese, and anemone-type blossoms. The single and Japanese bloom types usually perform much better in the South than the doubles do. In addition to the well-known white, pink and magenta flowers, newly available colors include yellow, cream and red.

Tree peonies also come in single, semi-double and double-flowered forms, and the color range includes every color of the rainbow except for blue. Depending on the cultivar and weather conditions, peonies will flower as early as March or as late as May. Tree peonies bloom a week or two earlier than herbaceous peonies.

Early blooming cultivars do best in the South as they have time to bloom before hot weather sets in. They are also less prone to botrytis blight.

Herbaceous Peonies: Modern hybrid peonies are complex crosses of other hybrids and several different species. Paeonia lactiflora is thespecies of many old-fashioned herbaceous hybrids and is often used to refer to them.

• 'America' has early, single, large, fiery red flowers with golden center tuft.
• 'Blaze' is a true red, early single with rounded petals and a sunny yellow center.
• 'Bride's Dream' is a creamy white Japanese. Center is soft yellow to cream.
• 'Coral Charm' has deep coral buds that soften to coral peach when open, with a gold center. Early, semi-double.
• 'Do Tell' is a Japanese midseason peony of shell pink with a rose, pink and white center.
• 'Felix Crousse' is a double Japanese flower type with ruby red flowers.

'Felix Crousse' peony
The Dow Gardens Archive, Dow Gardens, www.insectimages.org

• 'Festiva Maxima' has fragrant, large, early white double flowers with crimson flecks. Strong, tall stems and dark green foliage. This double old favorite does well in the South.

'Festiva Maxima' peony
Flickr: van swearingen. Creative Commons License 2.0

• 'Flame' is an early blooming rose-red single with a yellow center.
• 'Kansas' has large, early double flowers of watermelon red that hold their rich color throughout bloom time. This is one of the best doubles for the South.
• 'Miss America' has snow white petals that open to a full early semi-double. It is a heavy bloomer.
• 'Monsieur Jules Elie' has double pink flowers with silvery centers.

'Monsieur Jules Elie' peony
Flickr: Tie GuyII, Creative Comons License 2.0

• 'Paula Fay' is a glowing pink early semi-double with waxy textured petals.

Tree Peonies (Paeonia suffruticosa): Tree peonies form woody branches that do not die back, but simply drop their leaves in the autumn, as does any deciduous shrub. Their flowers are often larger than herbaceous peonies. Tree peonies like the same soil conditions as the herbaceous but require more shelter from the wind, and the larger-flowered varieties will hold their flowers for a longer time if protected from the sun during the hottest part of the day.

Tree peony flowers and plant habit
Wikimedia Commons, Shin- released to common domain.

• 'Age Of Gold' has creamy lemon semi- double flowers showing red flares at the base of the ruffled petals.
• 'Alice Harding' is an old tree peony that is not grafted and can be propagated by division. Double lemon flowers.
• 'Black Pirate' is an early midseason, single-or semi-double dark red, with darker flares.
• 'Dusky Maiden' is a dark red double flowered tree peony, with the flowers standing well over the bush. Green foliage with a hint of red-good autumn color.
• 'Gauguin' has unusual flowers of light raspberry red, flushed on the back and inside base of the petals with a pale gold.
• 'High Noon' has lemon yellow flowers that are red near the center. It may bloom again during the summer.
• 'Kamata-nishiki' is an early semi-double with dark purple, rose-like flowers.
• 'Roman Gold' is a free-flowering, wide bush with lemon yellow single flowers with red flares at the base of the petals.
• 'Taiyo' is an early semi-double with ruby red blossoms.
• 'Vesuvian' is an excellent compact bush with finely cut foliage, dripping with deep maroon double blossoms.

Fernleaf Peonies (Paeonia tenuifolia): These unusual peonies have finely divided fernlike foliage and deep red single or double flowers. They are dwarf in stature, and bloom very early. They are difficult to propagate and therefore are less available and more expensive.

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