Why do some Hydrangeas flower blue and some flower pink?
2. Answer: It has to do with the PH of the soil. Blue flowers come around if the PH of the soil is between 5.2 and 5.5. You can buy a PH test kit at a garden center. To lower the PH of the soil, you can add 2 table spoons of aluminum sulphate per gallon of water. You can also add organic mulch such as coffee grounds or pine needles to lower the PH. For your flowers to come out pink, the PH should be close to 7, and you can raise the PH of the soil by adding lime to the soil.
