Many gardeners think something has gone wrong when their hydrangea blooms and they find they bought a lacecap instead of a mophead. In the South, hydrangeas prefer morning sun and afternoon shade in a rich, organic-amended soil followed by a good layer of mulch. When the plants are growing and producing flowers, do not let the soil dry to the point of wilting the leaves. I grew up in Texas where the hydrangea blossoms are hot pink and was astounded at seeing my first ones in the Southeast that were blue. Both are beautiful, including those that are kind of purple, which indicates the soil has a neutral pH. It seems gardeners always want the opposite of what they have, so here is how it works.
Flower color is related to the aluminum available to the plant.
Aluminum is available in acidic soils and the flowers are blue. In alkaline soils, aluminum is not available, and the flowers are pink. So if you want pink flowers next year, modify your pH by watering into the soil dolomite limestone at a rate of about 1 cup per 10 square feet. This is not an exact formula as your soils may be at extreme pH levels. If this is the case, a soil test will come in mighty handy.