A frequent problem with peonies is the failure of flower buds to open in spring. Typically, the flower buds develop to about the size of a pea and then fail to develop further. There are several possible causes.  In a narrower interpretation bud-blast only includes environmental and cultural problems. In a broad interpretation, bud-blast includes fungal diseases that affect flower buds. The following are the most common reasons why peony buds may fail to open.

Botrytis blight

Botrytis blight, also called gray mold, is a common fungal disease of many plants including peonies. It commonly affects the new shoots and foliage of peonies (see Botrytis Blight of Peony herein) but can also affect young flower buds. The young buds turn brown and fail to open. Once affected, a flower bud cannot be saved. To address the disease in subsequent years follow the practices outlined in "Botrytis Blight of Peony."

Cold temperatures in early spring

When the young peony flower buds are subjected to cold temperatures in early spring as they begin to develop growth may stop when they are about the size of a pea. They may take on a reddish appearance but do not become brown and papery as in botrytis blight. Nor do they develop the gray mold characteristic of botrytis blight. Later in the season, however, the buds will brown and fall off. If possible, relocate peonies to a location where they are less subject to late spring freezes or protect plants when freezing temperatures are forecast.

Too much shade, lack of proper fertilization, or drought

Anything that stresses the plant could result in bud-blast. This can include too much shade – peonies prefer full sun, lack of adequate fertilization in poor soil, or a period of drought when the plants are making active growth and buds are developing in spring. Provide the plants with adequate sun, fertilizer, and moisture, especially in early spring when they are making active growth.

Plants are too young or have been recently divided

Newly planted or divided and transplanted peonies may take a year or two to become established before they flower normally. Be patient and give the plants good care.

Organic Strategies

Since bud-blast of peony is most often caused by environmental stresses, correcting the source of stress is the best way to prevent it. Proper site selection, as well as good division, planting, and watering techniques, are all organic approaches to preventing this condition. Proper fertilization is also recommended, and the use of organic fertilizers would be a viable organic approach as well