Answer: What you describe is normal for certain kinds of hydrangeas. Hydrangea blooms are made up of clusters of small flowers. The size, color and shape of the flowers vary from variety to variety. Hydrangea blooms contain showy sterile flowers and less conspicuous fertile flowers. What you are seeing are the fully opened sterile flowers around the edges and the tightly closed fertile flowers. Some hydrangeas are called mopheads because all the flowers in the cluster open. Some are lacecap which, like yours, has opened flowers around the edges and closed flowers in the center. So, I suspect you have a lacecap hydrangea. There's nothing you can do to change its blooming habit.
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