Why Are My Hydrangea Leaves Turning White

Powdery mildew manifests as a white powdery substance on the surface of the leaves. … Powdery mildew is most likely to be a problem on hydrangeas when the days are warm and the nights cool. You can prevent the disease by reducing humidity and increasing air circulation.

How do you get rid of white powdery mildew on hydrangeas?

Combine two to three drops of dish soap with ½ tablespoon of baking soda and ½ gallon (about 2 L.) of water. This will change the pH and prevent the mildew from forming or spreading. Mist leaves with the solution.

Why do hydrangea leaves turn silver?

Powdery mildew While this disease doesn’t usually kill hydrangeas, it can cause their leaves to drop. It’s characterized by a pale gray, powdery coating on the foliage. Powdery mildew spreads through spores, usually when the days are warm and the nights are cool. Remove and destroy any affected plant parts.