Care of Fern Peony

Named for its finely divided, feathery leaves, the fernleaf peony (Paeonia tenuifolia) is different from the common garden peony (Paeonia lactiflora). Fernleaf peony's foliage is delicate compared to common garden peony's large, solid leaves, and fernleaf peony is shorter and flowers about one week earlier. Hardy in U.S. Department of Agriculture plant hardiness zones 4 through 8, fernleaf peony is long-lived in full-sun, well-drained conditions. Common garden peony is hardy in USDA zones 3 through 8.

In fertile soil fernleaf peony needs little fertilizer, but it does need constant moisture in the growing season. If a plant is growing poorly or has small, pale leaves that aren't due to pests or diseases, apply a 12-4-8 granular fertilizer at a rate of 4 tablespoons per 4 square feet. Manufacturer's instructions vary between products, so read and follow the advice on the label. In warm zones, fernleaf peony often fades over summer. Don't mistake this fading for nutrient deficiency.

To maintain a constantly moist soil, water fernleaf peony when the soil surface is dry, but don't water it so much that the ground becomes soggy.

Removing a fernleaf peony's faded flowers helps keep the plant looking tidy. Fernleaf peony blooms appear in late spring or early summer, and plants flower for seven to 10 days. Removing the spent flowers allows the plant's delicate deep green leaves to remain attractive.

Check the plant every three or four days and remove flowers as the petals wilt. Pinch them off at their bases with your fingers, or prune them with pruning shears. If using pruning shears, wipe the blades with a cloth that was dipped in rubbing alcohol, before and after pruning fernleaf peony.

Old stems on a fernleaf peony can harbor diseases, but removing the stems reduces the risk of infection. Few diseases affect fernleaf peony. The main ones are botrytis blight and phytophthora blight, which cause wilting, discolored leaves and stems.

In late fall, when a fernleaf peony's leaves have died down, prune all the remaining stems to the ground with sterilized pruning shears. Collect the pruned stems and any dead plant parts and put them in the trash.

Fernleaf peony rarely suffers from any pests, but a common sight is ants on the flower buds and open flowers. Ants don't affect a fernleaf peony and are harmless.

While ants aren't a problem, sometimes flowers don't appear. If fernleaf peony flowers don't appear, it could be because the plant is too young or has been recently transplanted, or it has been planted too deep or too shallow. Other reasons for non-blooming include shady conditions and late frosts damaging flower buds. Fernleaf peony should be planted with the top of the root ball 1 1/2 to 2 inches below the soil surface, in a spot that receives at least four hours' sunlight per day. If frost is forecast, cover fernleaf peony with two or three layers of burlap, four or five sheets of newspaper or a cardboard box overnight.