One hydrangea bush can produce a variety of blossom colors depending on the soil content. Should the soil be high in pH the blossom are more pink; low pH results in blue blossoms. Some gardeners try to control the color of the blossom by added lime or aluminum sulfate to the soil. Our bush seems to be conflicted as it has a mixture of blue and pink blossoms. This could be caused because the shrub is planted at the edge of woods with oaks and pine. Yet, the bed it is planted in is limed each year. So, perhaps the acidic soil of the woods is creeping into the limed flower bed and creating a cacophony of color.