May is the month of exuberance in the garden. No matter how many false starts we have in early spring, all is forgiven this month. The grass greens up, the tulips come and go, and the next thing we know the lilacs are in bloom! But in this May madness, slow down enough to fully appreciate the flower that epitomizes spring’s glory, the beautiful peony (Paeonia spp.).
Peony plants are some of the oldest perennials in cultivation. Although they assume a shrublike stature at 2 to 3 feet in height and width, they are in fact true herbaceous perennials. Their leaves and stalks die to the ground after a killing autumn frost, but the rootstock remains very much alive, ready to send up those telltale red shoots the following April.
In spite of their delicate floral appearance, peony plants are strong, long-lived, and completely cold hardy, perfectly suited to Midwest weather. They resent disturbance and can live for 50 years if provided with their simple requirements. Their size and attractive habit make them suitable companions to all other border plants such as dwarf conifers, bulbs, and both early- and late-blooming perennials. Even though they bloom relatively early (May to early June), their stocky forms and ornamental foliage remain attractive all summer, well into autumn, when their leaves turn red as temperatures dip. At this time they are particularly valuable to late-blooming, prone-to-toppling perennials like asters, that will benefit from the healthy support system provided by the solid peony bushes.
Peonies are classified by the type of their blossoms or the time they bloom. Flowers are single, Japanese, semidouble, double, or bomb. The single and Japanese forms feature large, cupping petals that surround a center of bright yellow stamens (although a few of the Japanese flower centers are light and dark pink). The double forms hide their stamens inside never-ending petals; and the bomb flowers are recognizable by a flat outside row of guard petals, inside of which sits a fat "bomb" of tight petals. The hybridizing of peonies is an ongoing science, with new introductions marketed every year.
Peonies can be grown as specimen plants strategically placed in long or curving borders where they provide early structure as perennials begin to emerge. They can be massed in the back of low borders where they contribute an early showy flower display and then serve as a green backdrop for colorful bulbs, annuals, and perennials. By carefully selecting one single variety and locating plants side by side in a long row, gardeners can create a novel and quite ornamental peony hedge.
To extend the enjoyment of the flowers, choose a few early, mid- and late-season types so that all don’t bloom at once. While most colors are in the pink, coral, and red tones, there have been interesting developments in yellow. Consider how you want to use this plant before being swept away by the hundreds available locally and through specialty catalogs. Plant the fragrant ones close to a door or patio or use them as cut flowers. Never cut more than 25 percent of the blossoms from a plant in one season, taking care to cut short stems, leaving as much foliage on the plant as possible.
Plant peonies in the spring as potted plants or in the fall as bare tuberous roots. Cultivate the planting site thoroughly, add compost, and water well. In the fall, set the swollen roots no more than 2 inches below the soil surface. If planted too deeply, the peonies will fail to bloom. Mulch the area over winter just for the first year. Remember to cage your plants when they are 10 to 12 inches tall to support the heavy blossoms.
Peonies are susceptible to a variety of fungal blights that are exacerbated by wet, cool springs. Symptoms include blackened, splotched foliage; dark, dried buds that never open; or streaked stems. Approved fungicides are available and must be applied when the new shoots are 2 to 4 inches tall. Gardeners can reduce the chances of infection by spacing plants far apart, planting in well-drained soil in full sun, practicing good sanitation, and removing all dead foliage from the garden at the end of the season. So little effort for such heart-stopping beauty!