Peonies have large, fragrant blossoms that make them popular garden perennials. Peonies can grow up to 4 feet high, and may require support if they become that large. Peonies are hardy from U.S. Department of Agriculture planting zone 2 to zone 8, but they do not do well in subtropical zones. The dormant time during winter is necessary so the plant can bloom well the following year. Occasionally, you may find your peonies do not bloom as usual; many times you can correct the conditions that cause your peony not to bloom, but other times these conditions may be out of your control.
Trauma from weather conditions generally will not show itself until the next bloom. An extremely dry summer, for instance, causes peonies to have fewer blooms the following summer. A late spring or early summer freeze will also cause peonies to have blooming trouble the next year.
Undernourished peonies do not have enough fuel to create blooms. The plant itself will grow poorly and generally look unhealthy if this is the case. On the other hand, too much fertilizer will also cause your peonies problems. If given too much fertilizer, your peonies will have full, vibrant foliage but will not bloom.
Transplanting and Pruning
Pruning peony foliage too much or pruning late in the season, during July and August, forces the plant into a recovery mode and blooms the next season suffer. Moving your peonies also causes them to have trouble blooming. It can take up to three seasons for your peonies to recover enough to produce blooms after transplanting. When you either plant or transplant your peonies, be sure not to plant the bulb too deeply or the peony will also have difficulty producing blooms. You should only plant the bulbs as deeply as 2 inches.
Your peonies can be too old or too young to bloom. If you are starting your peonies from seeds, it can take up to five years for the plants to become mature enough to create blooms. Older plants can grow so large that they can no longer support blooms. In that case, you can divide the plant and transplant each portion.
Peonies require at least four hours of direct sunlight each day. If your peonies are in a shaded area, their blooms will likely suffer. If possible, you can move the peonies or prune branches that block light to your peony plants.