Answer: Hydrangeas should be pruned in early spring, just as the buds begin to swell. You can also do some pruning in the summer by cutting off the flowering stems, as far down as you like. This will promote new growth, especially in the center of the plant. The flowers on your hydrangea sound as though they are changing colors (either from blue to pink or pink to blue) because of your soil's pH. Blue hydrangeas will turn pink in alkaline soils; pink hydrangeas will turn blue in acidic soils. The lavender color is just a transition. Have your soil tested to learn what the pH is. Once you know whether it's acidic or alkaline, you can change it slowly over a period of a few years with soil amendments.
Best wishes with your garden!
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