Some types of big leafed hydrangea (Hydrangea macrophylla) will change color depending on the soil pH, with acidic soil encouraging the blue tones and a neutral soil enhancing the pink end of the color range. However, many of the newer introductions do not change color in response to the soil pH and those with a nominally red color normally would not react that way so you may not be able to change it on your plant. For some gardeners, this constant coloration regardless of the soil pH is considered a benefit. |