Posted on July 1, 2018July 1, 2018 by WILLEMSunday/ it’s hydrangea time My hydrangea is still going strong, and its beautiful summer flowers are coloring up. My hydrangea’s flowers are mostly pink. Hydrangea flower color changes based on the pH in soil. Acidic soil with a pH of 5.5 or lower will sprout blue hydrangeas; soil in between 5.5 and 6.5 will have purple hydrangeas, and a ph of 6.5 or higher will produce pink hydrangeas. White hydrangeas can not be manipulated by soil pH -they will always be white because they do not contain pigment for color.