Answer: Lack of light, a tender variety of over fertilization with nitrogen could be preventing your hydrangea from flowering, says Phil Waldman, owner of Roslyn Nursery, growers of 2,000 varieties of evergreen and deciduous shrubs in Dix Hills, New York. Hydrangeas need at least six hours of direct sun to bloom. The more light, the more blossoms, say Waldman. Nikko Blue hydrangea sets flower buds on the previous year's growth. The buds are marginally hardy in this area and often are winter killed. In addition, hydrangeas are vigorous growing shrubs. If they're over fertilized with nitrogen, often as a result of too much high nitrogen lawn fertilizer used on the lawn around the shrub, flower buds won't set, he explains. To get your hydrangeas to bloom, try moving the shrubs in early spring or fall to a sunny spot where they're protected the wind. Don't use lawn fertilizer on the grass around the shrub and apply a fertilizer high in phosphorus and potassium such as 5 10 10 in spring, says Waldman. If you're planting a new blue hydrangea, try growing a cultivar that's hardier and sets flower buds on the current year's growth, such as All Summer Beauty, he adds.
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