The Genus Paeonia

Other problems that may cause difficulties are related to site selection and cultivation. Avoid planting peonies in cold pockets in the garden where late spring frosts can damage new shoots, developing foliage and flower buds. Each species and selection will show some variability in its susceptibility to frost damage. Timing and severity of frosts will vary with the stage of development of the plant, so that plants that emerge early in a climate with late frosts can be severely damaged, while late emerging species subject to similar frost conditions may show no harm. Mediterranean species may be especially sensitive to late frosts.

Symptoms of frost damage may be a failure to bloom or severely reduced flower productions. Some buds may simply die on the stem. Leaves may be curled and crinkled or, in most severe cases, terminal parts of a stem may be dead. Peonies in general show considerable frost tolerance and shoots may be bent over 180 degrees from an overnight frost, but return to an upright position and bloom normally later in the season.

Care in planting is most important, but some protection may be needed, too. Cover the most susceptible tender young plants with a light woven or non-woven fabric on cold nights. Do not use plastic, which traps moisture and conducts cold directly to adjacent leaves. Some specialists construct lightweight portable boxes to cover very sensitive and rare plants. Experience with the needs and abilities of each species will improve your success in difficult areas.

Drainage and related water damage should also be considered. As mentioned, most peonies need very good drainage and prefer sites that are not waterlogged or do not remain wet. Heavy spring rains may form pools in and around plants for extended periods. Excess drainage from gutters and downspouts may unknowingly lead to delicate plants. Symptoms include a collapse of leaves, stems or the whole plant. Heavy water soaking reduces the amount of air flow to roots and the plant can suffocate and die.

Correction of these conditions may be difficult if they are not detected early, and the plant may die. Divert water away from the crown of the plant. Move the plant in the fall, while dormant, or apply one of the products used for absorption of excess water (sold under various brand names including Turface). Conditions must be corrected or the plant will suffer and decline. Avoid sites that routinely hold excess water.