Angie,
I would be very happy if my hydrangeas gave me that color. It is much better than the horrible light pink they were this summer. Problem is, I didn't plant these hydrangeas and I know whoever did never bothered to amend the soil or even think about soil pH and bloom color.
Large amounts of pine needles, and also oak leaves, help to acidify the soil as they break down. However, for alkaline soil like ours it is not really a practical solution.
Corey
