K & K Gardens offers both bush peony (considered herbaceous perennials), and tree peony (Paeonia suffruticosa), which are woody perennials.
Peony plants bear an attractive, glossy green foliage that reaches 2'-3' in height with a similar spread. Their popularity is due mainly to the flowers. The most striking peony flowers are the highly fragrant, massive doubles, usually pink, red or white. Other colors and flower types do exist, however. There's even a hybrid with yellow flowers. Peony plants bloom in late spring or early summer.
Botrytis blight and other diseases may affect peony plants. Becareful peony plants, grouped en masse, do not become too crowded. Overcrowding reduces air circulation -- an open invitation to disease. If you experience this problem, make a habit of keeping the foliage trimmed back, so that one peony plant does not touch another. A preventive measure is to space peony plants sufficiently when planting (3'-4' on center).
Peony plants prefer full sun. Grow peony plants in a soil that is fertile and well-drained, with a pH of 6.0 - 7.0.
Peony plants grow in zones 2-9. Plant bare-root peony plants in fall. All you'll see is a crown with roots dangling beneath. Dig a shallow hole, spread the roots apart and set the peony plant in the hole. Take note of the buds, which look like the "eyes" on potatoes. The buds should rest only 2" under the surface when you are done planting, otherwise, you may have trouble getting your peony plants to bloom properly. For potted peony plants, a spring planting is suitable.
Peony plants sometimes are planted individually, or by sharing perennial beds with other perennials. In this case, they should be planted in back. Peony plants are also often planted in groups, side by side, and to form a row. When used to form perennial borders, they can make a bold statement in the yard.
Support peony plants with stakes or hoops, as you would tomatoes. The large blooms get heavy, especially after a rain. Trimming back and disposing of the foliage in autumn helps prevent the disease, botrytis blight. Other diseases may cause a gradual decline in peony plants. If you see one specimen is stunted while the peony plants around it are doing fine, remove and destroy that plant.
The standard pronunciation is pee'-uh-nee (accent on the first syllable). However, many people place the accent on the second syllable: pee-oh'-nee.
Often, when we see pictures of huge, beautiful flowers in books, we assume they come from the tropics. Happily, Mother Nature made an exception with peony plants. Cold hardy to zone 2, deep in the frozen North, peony flowers needn't take a backseat to any tropical bloom.
As is fitting for such a lovely flower, peony plants derive their name from a Greek myth. Paeon, a student under Aesculapius, god of medicine, was well aware of the medicinal qualities of peony plants. He used them to heal a wound suffered by the god, Pluto. The upstaged Aesculapius wasn't pleased and threatened retribution, but, in one of those charming metamorphoses sprinkled liberally throughout the pages of Greek mythology, Pluto saved Paeon's life: he turned him into a peony plant.
If possible, try to grow peony plants near entrances, where their fragrance can be most readily enjoyed. While their blooming period is tantalizingly short, even the foliage of peony plants is sufficiently attractive to warrant planting in a cozy corner near the doorstep. The peony plants with double flowers tend to be the most fragrant. To extend the blooming season, "stagger" your selection of varieties. That is, select some that bloom early, others late, and still others that bloom sometime in between.
As if stunning beauty and heady fragrance weren't enough, peony plants are also exceedingly long-lived. Peony plants are unlike many other perennials, in that they do not need to be divided on a regular basis. In fact, they dislike being disturbed.