Answer: Hydrangea flower color can be affected by soil pH and also by the weather. All hydrangea flowers start out green and then turn pink, blue or white. If yours remained green it indicates they never matured. This can be due to lack of sunshine and/or heat, or too much nitrogen fertilizer (which redirected the plants' energy into producing vegetative growth rather than maturing the flowers). I suspect everything will be alright with your plant next year - sorry you'll have to wait until next summer to enjoy those luscious pink blooms.
Best wishes with your hydrangea!
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