Though a few species peonies may be found through specialists’ catalogs and seed exchanges, most garden peonies are hybrids. The basic types are herbaceous and tree peonies, both descended from Chinese species. A new third category, the intersectional hybrids, combines the best traits of herbaceous and tree types. All peonies are extremely long-lived plants of significant size; they provide choice cut flowers and are a mainstay of big perennial borders.
Plant peonies in fall, either as bare-root plants or from nursery containers. Ideally, the planting site for peonies should be deeply dug at least several days before planting. Work in plenty of compost, especially in heavy soil, and incorporate a high-phosphorus fertilizer; then allow the soil to settle before planting.
Peonies of all types can be grown in large (18–24-in.) containers. Replant every third autumn in the same or a slightly larger pot, replacing most of the soil when you do.
Perennials. Well-grown clumps reach 2–4 ft. tall and wide. Large, glossy, deep green, attractively divided leaves are an effective background for the plants’ spectacular spring or early-summer flowers and look good throughout summer. Flower colors range from pure white through cream to pink and red; some of the reds are very deep, with chocolate brown overtones. Depending on the variety, blossoms range from 2 in. to as much as 10 in. across; many have a perfume similar to that of old-fashioned roses, though in some varieties the scent is either unimpressive or absent. In form, they fall into three basic categories: single or semidouble, with one or two rows of petals; Japanese, with a single row of petals and a large central mass of narrow petal-like segments called staminodes; and double, with full flowers composed of many petals. Varieties are too numerous to list.
Herbaceous peonies bloom well only where they get an extended period of pronounced winter chill. Summer heat is not a problem for the plants, but their flowers do not last as well where spring days are hot and dry. In such areas, choose singles, semidoubles, and Japanese varieties, as they bloom before the season heats up; also give plants some afternoon shade and be sure they have adequate water. (Japanese types in particular do well in the warmest zones.) In the mildest-summer parts of Zones 1–7, where these plants grow best, they thrive in full sun. Provide support for very large or double varieties, which can become so heavy with water during spring rains that they fall over.
Divide herbaceous peonies only to increase your stock. Dig clumps in early fall, hose off soil, and divide into sections, making sure that each has at least three eyes; these appear at the tops of root clusters, at or near the bases of the past season’s stems. Plant immediately to allow plants time to put down roots before the onset of freezing weather. Transplants may take a year or two to establish before blooming.
Woody perennials. Moderate growth rate to about 3 ft. high and wide. Attractive leaves resemble those ...
Perennials. Well-grown clumps reach 2–4 ft. tall and wide. Large, glossy, deep green, attractive...
Arctic and mountains of North America, Eurasia. Small (1/4 to 1/2-in.), narrow bright green leaves for...