The varied colors of flower petals depend on pigments such as anthocyanins and betacyanins. Anthocyanins are a group of several complex compounds. It is incorporated into the cells as a glycoside. The color of the flower changes when the pH of the soil changes. If the pH of the soil is acidic, the color of the flower is red, if the pH is alkaline, the color of the flower is blue, and if the pH is neutral, the color of the flower is purple or dark blue.