Culture
Easily grown in rich, fertile, medium moisture soils in part shade. Add compost as needed before planting. Each plant will flower for approximately 7-10 days. Remove spent flowers after bloom unless viewing the attractive seed pods is desired. Cut foliage to the ground and remove from the garden in fall after frost. Plants are long-lived, do not need to be divided and can be left undisturbed for years.
Noteworthy Characteristics
Paeonia japonica, a herbaceous (soft-stemmed) peony, is a woodland species that is native to certain islands in northern Japan and is noted for its compact size, single blooms and preference for part shade. It is a small shrubby plant that, each year, will typically grow to 18" tall by mid-spring, bloom, display attractive foliage throughout the summer and early fall, and then die to the ground after frost. Single, white, cup-shaped blooms (to 3" diameter) with yellow center stamens appear in mid-season (usually May in St. Louis). Blooms are fragrant. Blooms give way to seed receptacles which split open when ripe (late summer) to reveal attractive blue seeds on red stalks. Gray-green foliage is divided into oval to lance-shaped segments. This species is very similar to P. obovata which is a woodland species native to Siberia and China, and some authorities (e.g., Hortus Third) consider P. obovata var. japonica to be synonymous with P. japonica.
Genus name comes from the Greek name for Paeon, physician of the gods and reputed discoverer of the medicinal properties of plants in this genus.
Specific epithet means of Japan.
Problems
Peonies are considered to be relatively pest free. Botrytis blight and Phytopthora blight are sometimes problems. Ants on peony buds are common and totally harmless. If plants do not flower, possible causes include: (1) planted too deep or too shallow, (2) planted in too much shade, (3) late frost killed flower buds or (4) plant is too young or has been recently moved or disturbed. Blooms do not need staking or other support.
Uses
This is a compact woodland peony that is best suited to open woodland or shade gardens or to shaded areas of the border. Also could be effective as a low herbaceous hedge or edger. Flowers are extremely showy, and foliage remains attractive throughout the growing season either alone or in combination with other flowering/foliage shade perennials such as hostas.