Tips for growing Hydrangea - Hydrangea are a wonderful flowering shrub. The blossoms can be very large and come in several colors: Red, Pink, Blue, Purple and White. Some varieties have blossoms of different colors. The color of the hydrangea flower really varies with the amount of aluminum ions in the soil. Acidic soils with a pH of less than 5.5 produce blue flowers; soils with a pH greater than 5.5 product pink flowers. White flowers are not affected by pH.