There are some hydrangeas such as Endless Summer where you can change the flower color. And, with those types, a lower pH makes the flowers blue and higher pH turns the flowers pink. Vanilla Strawberry is different. The flowers start off green-white. Then, when the temperatures drop later in the summer and it cools down, the flowers turn reddish-pink. If your late summer night temperatures are still quite warm, the hydrangea may not have that opportunity to change color.
MY VANILLA STRAWBERRY HYDRANGEA HAS BLOOMED WHITE IN COLOR BUT HASN’T TURNED PINK. WHAT CAN I DO?
Vanilla Strawberry Hydrangea’s flowers open up green-white.