More than 30 peony species and approximately 3,000 peony cultivars are in existence, according to the University of Missouri Extension website. Peonies are commonly grown in home gardens because of their showy flowers, attractive foliage and versatility.
Peonies are generally divided into two groups. Herbaceous peonies include the officinalis, lactiflora and tenufolia species. They grow between 2 and 4 feet tall, with alternating oval-shaped or elongated leaves. They produce every blossom color except for blue, according to the University of Rhode Island website. Tree peonies include the suffruticosa, lutea and rockii species. They grow as tall as 6 feet in height, with blossom forms that vary by cultivar.
Peonies are hardy in USDA zones 3 through 8. Peonies thrive in full sunlight, but they tolerate light shade. They require nutrient-rich, moist, well-drained soil; they tolerate a variety of different soil types.
The University of Vermont website indicates that some cultivars may not bloom in zone 8 because of the lack of cold weather. Peonies are occasionally attacked by scale insects. They are also susceptible to fungal infections such as verticillium wilt, phytophthora blight and botrytis blight.