Peonies are a herbaceous, perennial plant known for its large, showy, rose-scented flowers. They are often found in home landscaping because of their long-lived growth habit and easy maintenance. Peonies will produce blossoms year after year with a minimum of care and are hardy in USDA Hardiness Zones 4 to 7.
Peonies grow best in cool climates. They need 100 to 300 of chilling hours in order for them to bloom, according to North Carolina State University horticulturist Erv Evans. Many cultivars do not grow well in the South because of the lack of cold temperatures required for these plants to bloom. Peonies also need a full sun location, but they tolerate some shade. These plants need well-draining soil and do not like "wet feet," which can rot the rhizomes from which they grow. The soil pH should range between 6.0 to 7.0. Plant peonies in the fall, giving them plenty of room to spread. If planted in spring, they may not bloom for a year or two. Add 5-10-10 fertilizer each spring before the growing season. Do not overfertilize. Peonies will die back to the ground each winter.
When peonies bloom depends on environmental conditions and the type of cultivar. Some peonies are early-blooming varieties while others bloom later in the spring. Peonies are a short-lived flower that only lasts for one week, according to the University of Rhode Island web site. Blooming can be extended over several weeks by planting early, mid-term and late-blooming varieties to give your garden up to six weeks of peony flowers.
Peonies benefit from a layer of mulch to keep moisture around roots and to control weeds. Remove the mulch in the fall to prevent disease contamination. Leave the plants unmulched over the winter months. To improve blooming, remove side buds, leaving only the terminal buds to flower. After blooming, remove the old bloom, cutting just below the head and leaving as much foliage as possible.
Peonies will not bloom if planted too deeply. The "eyes" on the rhizome should not be more than 2 inches below the surface of the soil when planting, according to Paeonia. Peonies will not bloom if they do not get sufficient sunlight during the day. Move plants to a different location or trim nearby foliage to allow more sun on the plants. Peonies also dislike being transplanted and will take some time to re-establish after being moved. Divide in the fall only if plants become too crowded. Too much fertilizer can also affect blooming. Fertilize only in the spring or if plant appearance indicates a need for additional fertilizer.