Peonies are a classic, commonly grown perennial whether found in the gardens of stately homes or planted around the humblest farmhouse. They're everywhere, gracing Western Pennsylvania gardens with their glorious, sweetly scented blooms in late May and June. Few diseases bother them, and they are exceptionally long-lived plants. With a careful selection of early, middle and late-season cultivars, their bloom period can last several weeks.
Gertrude Jekyll, (1843-1932), the famous English garden designer, writer and artist, wrote that each spring she could not wait to see the "dear rosy snouts" of the peony as they poked through the earth. The delicate emerging growth is a harbinger of the upcoming growing season. And then there are the flowers, those huge, luscious blooms that are the main reason we grow peonies. They come in shades of white, red, pink and, now, with intersectional hybrids, hues of yellow and lavender, too. Many peonies are fragrant, with a scent that rivals the rose. If selecting peonies for fragrance, the double pink varieties tend to have the heaviest scent.
Peony flowers come in a variety of shapes and forms. Large double flowers, such as 'Festiva Maxima,' are most common. Single varieties such as 'Krinkled White' and Japanese cultivars such as 'Bowl of Beauty' are among my personal favorites. The single types have flower heads that are smaller and tend to stand up to thunderstorms better than the doubles.
After blooming, the plant happily occupies space in the perennial garden with a mound of glossy, deep green foliage, which serves as a fine complement to its neighbors in the bed. In the fall, peony foliage displays autumn color in shades of orange, yellow and red. Do not cut the plants back too early and miss the final hurrah of this glorious plant.
Culture for the herbaceous peony is simple. A dear gardening friend shared the old adage of the number 9: Peonies should be divided or planted or moved on the ninth day of the ninth month at 9 a.m. It is a good way to remember the optimal time to plant peonies.
In September or early October, find a sunny, well-drained site free from the competing roots of trees or shrubs. Dig a large, bushel-basket-sized hole, and incorporate organic material, such as compost or leaf mold, into the soil. Purchased peonies are often shipped bare-root. If you're dividing an existing plant in fall, rinse all of the soil off of the roots and divide and replant. Be sure each division has two or three "eyes" -- places at the crown of the plant where stems have originated. Place the bare-root plant with the red eyes pointed upward and cover the eyes with no more than 1 or 2 inches of soil. Peony eyes planted too deeply often fail to bloom.
If you can't follow the adage of the "nines," rest assured that these tough plants can be moved at almost any time. If the plant is in full growth, choose a cooler day to dig and preserve as much soil around the roots as possible. Water deeply and shade the plant if possible. You might lose some foliage or flowers, but prune out the growth that doesn't survive and give the plants a year to recover.
Peonies also need lots of sun, so be sure your site gets at least six to eight hours. Top dress each spring with compost worked lightly around the roots, being careful not to break the tender shoots. A light application of a complete fertilizer, not too rich in nitrogen (such as 5-10-5), after the plants flower, is also helpful. I alternate every other year with a handful of bone meal, worked into the soil around each plant. It is an organic fertilizer that is high in phosphorous and encourages bloom. Too much nitrogen causes excessive green growth at the expense of flowers.
Botrytis is a common fungal disease affecting peonies. Often plants bloom well, but they will have a few buds that don't open and turn brown or become gray and fuzzy. Leaves also can develop spots or wilt. Prune the affected parts of the plant and clean your pruners after cutting. In the fall, be sure to cut the plant down completely to the ground, being careful to discard all foliage and stems in the trash and NOT the compost pile. This year-end care of peonies is wise regardless of whether your peonies have been affected by botrytis.
Staking for peonies is usually a must, particularly because our area is prone to heavy rains in June, usually just about peony bloom time. Often, because the blooms are smaller and lighter, the Japanese and single types will weather rains without their flower heads landing in the dirt. If you're disinclined to stake your flowers, these are a better choice than the heavy, double varieties.
Peonies make a stunning cut flower. They are best cut before fully opened, when the bud is showing color and are as soft as a marshmallow. You can also rescue peonies that are heavy with rain and place them in arrangements. If cut in the bud stage, it's very easy to rinse ants from the blossoms, but a gentle rinse works for open flowers too. The ants aren't eating the peonies but enjoying the sugars present on the blossoms.
Most gardeners acquire their peonies from generous friends who've divided heirloom plants or from a garden center. For the greatest selection of peonies, check out online sources. Cultivars can be chosen for specific bloom times, fragrance or for newer varieties.
Finally, remember the peony is not a plant for the impatient gardener. Newly set bare-root plants may take up to three years to become established. The first and second year's growth and bloom may not be too impressive. Ultimately, the gardener will be greatly rewarded with a plant that will only become more bountiful each year and will probably outlive the one who planted it.
Bill Goff is a Penn State Master Gardener. Columns by Master Gardeners will sometimes appear in place of the Garden Q&A by Sandy Feather, a Penn State Extension educator.