Peonies are herbaceous perennial plants that exhibit an abundance of large, colorful flowers every spring. These plants typically grow 2-4 feet in height and produce several types of aromatic flower forms in varying shades of pink, red, purple, yellow and white. Used as an attractive accent along an evergreen shrub border, divided along property lines and driveways or an interesting backdrop for annual flowers, peonies provide color appeal and splendor to many garden areas.
Fall is the optimum time to plant peonies. Although peonies can be planted in the spring, the plants may not produce blooms for a year, possibly two. Plants prefer sunny or lightly shaded locations in well-drained soil with a pH of 6.0 to 7.0. Peonies require cold temperatures through winter to bloom the following spring, so it's preferable to plant them in areas with northern exposures.
Cultivation and Spacing
Dig holes at least 18 inches wide and 12 to 18 inches deep, spaced 3 to 4 feet apart from each other. Compost, manure, topsoil or pine bark should be incorporated into the soil before peonies are planted. Each peony should have at least three to five healthy buds, or eyes, per root. With the buds pointing upward, cover roots with no more than 2 inches of topsoil after planting. Peonies planted too deeply may fail to bloom properly the following year.
Propagation and Division
Divide older, well-established peonies when blooming is reduced due to root overcrowding. Trim the foliage to two inches in length, and carefully dig up the roots with a spading fork or shovel in the fall. Shake off the excess soil and then wash off any remaining soil. Divide clumps into three to four roots with three to five buds per root, then plant as directed.
Staking and Fertilization
Peonies often become heavy when in bloom, causing the stems to bend or break. Place a stake behind the plants, and then secure stems to the stake with plastic-covered garden ties. Peonies can benefit from applications of manure or commercial fertilizers. For best results, apply a 1- to 2-inch layer of manure to the surface or work two tablespoons of 5-10-5 fertilizer into the soil in late fall or early spring. Keep any type of manure or fertilizer at least 12 inches away from the stems of the plant.
Disbudding peonies is recommended for plants to produce larger flowers. As soon as the buds begin to appear, trim off all the side buds, leaving the terminal bud on each stem tip.
Pests and Diseases
Peonies are not usually affected by pests; however, scales can be occasionally seen on stalks and leaf bases. Insecticidal soaps and oils can be applied to control scales, but read all labels thoroughly to prevent damaging the plant. Avoid overhead irrigation and overwatering, to keep diseases such as leaf blotch from occurring. Other fungal diseases, such as Phytophthora blight and Verticillium wilt, can only be controlled by destroying affected plants.