The crowning glory of the spring garden, hardy, long-lived peonies (Paeonia) are so easy to grow and flower so reliably that every gardener should make space for them, even in warm climates, where early bloomers with low-chill requirements are suitable. In many parts of the country, if you choose plants carefully, you can enjoy the sumptuous blossoms for up to six weeks.
Peonies are divided into two groups: herbaceous peonies, perennials that grow to about three feet tall and die back to the ground each winter, and tree peonies, slow-growing woody-stemmed shrubs that can reach up to six feet at maturity. Once established, both types live for decades.
These bushy perennials are classified as early-, mid-, or late-season bloomers, each flowering for about two weeks in spring. For blooms from midspring to summer, choose peonies from each group, and be sure to include some that are especially fragrant or long lasting in bouquets. Most are hardy in Zones 2 -7, but some are suitable as far south as Zone 8.
'Bowl of Cream' (Zones 2–7) bears very large, double, pure-white flowers in midseason.
'Butter Bowl,' (Zones 2 - 7) a midseason bloomer, bears Japanese-style flowers with ruffled yellow centers surrounded by pink petals.
'Coral Supreme,' (Zones 2 - 8) one of Martha’s favorites for its large, globe-shaped, semidouble, salmon-coral flowers, is an early bloomer.
Golly' (Zones 2 - 8) has unusual double flowers with soft-pink guard petals and a yellow center surrounding a tuft of pink petals in midseason.
'Green Lotus,' (Zones 2 - 8) an early bloomer, bears large, distinctively fringed white blossoms streaked with lime-green and soft-pink highlights.
'Karl Rosenfield,' (Zones 2 - 7) a free-flowering mid- to late-season bloomer, has large, globe-shaped, double, crimson blooms that are excellent for cutting, lasting about a week in a vase.
'Sarah Bernhardt' (Zones 2 - 8) bears globe-shaped, double flowers that fade from pale pink to blush on the outer petals and are occasionally flecked with carmine. The late-season flowers, which last about 5 days once cut, are ideal for bouquets.
Truly four-season plants, tree peonies have attractively cut leaves that drop in fall, revealing shaggy-barked stems and an interesting silhouette in winter. The many branched shrubs bear six- to twelve-inch-wide flowers a little earlier than herbaceous peonies. Most are hardy in Zones 4 - 8, and some are suitable to Zone 9.
'Bai Yu,' (Zones 4 - 8) a good choice for gardeners in warmer climates, has fragrant, double, white flowers that open midseason, revealing deep-yellow stamens.
'Leda' (Zones 4 - 8) bears fragrant semidouble deep-pink flowers with purple flares and gold stamens in midseason.
'Marchioness' (Zones 4 - 8) produces an abundance of fragrant apricot-blush flowers with raspberry flares at the base of each petal and gold stamens in midseason.
Planting Bare-Root Peonies
Although peonies are often sold in pots (and can be planted like other container-grown plants), they are also sold as bare-root plants for fall planting, about six weeks before first frost in your area. Peonies often live more than fifty years, so it’s important to select the right site and to prepare a fertile, well-drained planting bed.
1. A few weeks before planting, choose a sunny to partly sunny site (in warmer regions, blooms last longer when provided with afternoon shade) with neutral to slightly alkaline soil. Dig plenty of compost or well-rotted manure and some bonemeal or high-phosphorus fertilizer into the top foot of soil.
2. Unpack and examine the roots; if they appear dry, soak them in water for a few hours. Dig a hole, and set the peony root with its eyes (pink growth buds) facing up, about 2 inches deep. If planting tree peonies, make sure the graft union (the point where the root meets the trunk) is below the soil.
3. Water thoroughly, and mulch during the first season.
Why Peonies Fail to Bloom
Immaturity. Peonies can take 3 - 5 years to reach maturity and may produce few or no flowers until then. Some double types will produce both single and double flowers until they mature and then produce fully double blooms.
Climate. Peonies require cold winter weather to induce dormancy and flowering. In warmer regions (Zone 8), gardeners should choose early-flowering peonies with single or semidouble flowers.
Planting Depth. Most peonies planted deeper than 3 inches will not flower. In the warmest regions, set eyes of the roots 1 inch deep, in colder regions, set them 2 inches deep, and if the soil is very sandy, set them 3 inches deep.
Insufficient Light. Like many flowering plants, peonies need direct sun to flower. Peonies will not flower or will flower sparsely if they receive less than four hours of sun.
Overfertilizing. High-nitrogen fertilizers promote green growth at the expense of flowers. Do not overfertilize peonies: Apply bonemeal or fish emulsion in early summer after plants have bloomed.