A: Those spots are due to Cercospora leaf spot, a fungus. Since the hydrangea will lose its leaves soon anyways, don’t worry too much now.

Once they fall, rake all the leaves out from under the plant and dispose of them, since they have fungal spores on them. Next year, as new leaves come out, spray all new growth with a fungicide to keep the leaf spot from returning.

Good hygienic practices like these keep fungal spores from overwintering near the soil and spreading on the plant during the next season of active growth. Another task is to remove leaf litter debris from the center, or crown, of a hydrangea once it’s lost its leaves. This ensures good airflow through the center of the plant and that insects don’t overwinter and damage the plant there.

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