Very few plants can beat the attractiveness of the peony plant's lush green foliage and bright blossoms, according to the University of Rhode Island, which says they're one of the best perennials for the backyard garden. Landscapers will find peonies relatively low-maintenance, but occasional trimming and pruning can help maintain the plant's lush look and encourage vigorous health.
Trim the stems of the peony plant as soon as the growing buds appear on the stem. North Carolina State University suggests removing all side buds except the main bud on the stem tip. This encourages the plant to produce bigger blossoms.
Deadhead the plant by cutting off the plant's blossoms as soon as they wilt. This keeps the peony from producing seeds, which drain the plant of energy and reduce flower production. When trimming spent blossoms, make the cut at the flowers' stems and avoid trimming off any foliage.
Cut back the peony after the first frost in your area if it's a garden peony (Paeonia spp.). Don't do this for tree peonies (Paeonia suffruticosa), according to North Carolina State University. The university recommends cutting the plant down to a height of approximately 3 inches.
Prune the peony if it's afflicted with fungal diseases like powdery mildew, which can sometimes appear on garden plants that are kept too wet. Trim off diseased foliage or stems as soon as you notice disease symptoms. This keeps the disease from spreading to other parts of the peony or jumping to other garden plants. When trimming diseased peonies, the University of Nebraska advises sterilizing your pruning shears afterward so you don't spread any fungus or bacteria spores. Dip the shears in a solution made by combining one part household bleach with nine parts fresh water.