Answer: The color change is not especially normal, but it does happen, depending upon the soil in which it is growing. The flower color is determined by the availability of aluminum in the soil. In alkaline soils, the aluminum in the soil is in a form that is unavailable to the plants. In soils with a pH of 7 to 7.5, expect pink flowers. In acid soils, the aluminum is in a form that the roots can take up, so in soils with a pH of 4.5 to 5.5, expect blue flowers. In between, in soils with a pH between 5.5 and 7, the color will range from bluish to mauve to pinkish.
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