Answer: Hydrangea blooms do age and as this happens, they fade so you won't see the brilliant color for more than about 3 weeks. Typically, though, they open their flowers in stages so that you'll usually have different sizes of flowers in the process of opening and maturing. I would clip off the flowers as they age. This will promote new blooms and the aging ones won't detract from the rest of the plant.
Best wishes with your garden!
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