Peonies (Paeonia spp.) are cold-hardy, perennial flowers desirable for their large, fragrant blooms. There are two types of peonies that are commonly grown in home gardens, according to Ohio State University. They are the garden peony (Paeonia hybrids) and the tree peony (P. suffruiticosa). Both types of peonies make showy, long-lasting cut flowers and will grow well with only basic care.
Peonies are temperate climate plants. They will not grow well in tropical or subtropical climates. These perennials need a chilling period in order to bloom. For that reason, they grow best in U.S. Department of Agriculture plant hardiness zones 2 through 8, according to Ohio State University's website.
Garden peonies vary primarily in the shape of their flowers, which can range from single (five petals) to the elaborately ruffled anemone peony. Tree peonies are shrub-like in form, according to North Carolina State University. They are known for producing large amounts of flowers and do not die back down to the ground in winter like garden peonies do. Peonies flower in a wide variety of colors ranging from deep black to pale pink, from bright red to creamy white, and shades of yellow and coral.
Sizes and Growth
Garden peonies grow to a maximum height of 3 feet, with a maximum spread of around 4 feet. Tree peonies grow to a maximum height and width of 5 feet. These plants are actually quite slow growing, but they can live a very long time--up to 100 years, according to Clemson University. Most do not start blooming until after the third year of planting.
Peonies need at least six hours of sun to bloom well, according to Clemson University, and will benefit from afternoon shade in the hotter growing zones. This is especially true in the case of tree peonies, as the intense rays of the direct light from afternoon sunshine can damage the delicate flower petals. Well-draining soil is vital. Overly wet or heavy soil can cause root rot, which will kill the plant. Peonies also prefer a soil pH level of 6.5 to 7.0.
Fungal diseases can plague both types of peonies, according to North Carolina State University. These diseases spread on water and can be especially bad during wet springs. Botrytis and phytophthora blight present as black or rotten spots on the new buds. The disease can also affect the leaves and the stems of the plant. Prune off affected parts of the plant and clean up and destroy any dropped leaves, as the disease can overwinter in the soil. Prevent these diseases from occurring by giving your peonies plenty of room for air to circulate around them and by watering at the ground level so as to avoid letting water sit on the leaves. Or apply a fungicide in early spring as a preventative measure, following the directions on the label for the size of your plant.