Peonies are old-fashioned perennials that bloom large colorful flowers in late May, right around Memorial Day. Peonies need about two to three years to begin blooming, depending on the size of its tuber. However, there are occasions, either due to the fault of the gardener or the weather, where peonies will fail to bloom or produce smaller than normal blooms. Some causes of little to no blooms are overfertilizing, disease or cold weather.
A peony could have no blooms due to a problem with its planting location or how it was planted. Plant peony tubers with their eyes no more or less than 1 to 3 inches below the soil surface. If planted too deeply, the peony could delay blooming or even not bloom at all. When it has been in a location for several years without supplemental fertilization, the soil could become depleted of needed nutrients. This could cause the flowers to stop blooming and the stems to become yellow and spindly. Should this occur, apply the proper type and amount of fertilizer for your soil’s needs. Peonies also need a location where they can receive at least 6 hours of full sun each day in order to produce large blooms. Carefully transplant the flowers to a sunnier location come September if they aren’t receiving the proper amount of sunlight.
If peonies are given a fertilizer that contains too much nitrogen, they could fail to bloom but have an overabundance of foliage. They prefer well-balanced organic fertilizers that contain low to medium amounts of nitrogen, usually in the combination 5-10-5 (nitrogen-phosphorus-potassium) in the early spring and again just after flowering.
Two common diseases, botrytis blight and Phytophthora blight, occur in peonies and may cause them to fail to bloom. To counteract these diseases, practice good sanitation by removing foliage in both the fall and the winter. Use fungicides to help control the problem as needed.
A late frost could damage any developing flower buds and cause peonies not to bloom. They could also not bloom if the conditions are particularly dry. Water the soil thoroughly to depths between 12 and 18 inches. To accomplish this without drowning the flowers, use a slow, gradual irrigation of about 2 inches.