Answer: The most common reason(s) for hydrangeas not blooming are winter dieback and/or pruning at the wrong time. Hydrangea macrophylla (the most common group of hydrangeas) blooms on wood that grew the year before. If winter cold kills back the old stems, then the plant won't bloom the next summer. Likewise, if you prune the plant in fall, winter, spring, or early summer you will be cutting off blooming wood. The best time to prune these is right after they bloom in the summer. If your plant is suffering a lot of winter damage, it may be that it is root hardy but not bud hardy in your area. Often, too, freak spring frosts can damage the flower buds even if they have managed to survive the winter. Sometimes providing a wind break or moving the plant to sheltered location protected from wind can help. I hope this helps you trouble shoot.
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