Hydrangea – Leaf Spot
Q: I planted two hydrangeas a year ago. The leave are now covered in round brown spots and they are not blooming. What should I do?
A: Hydrangeas commonly get a leaf disease called Cercospora leaf spot in summer. It usually infects when leaves are regularly wet by rain or irrigation or when planted against a wall that inhibits air circulation. It can also be a problem when the shrubs grow so densely that leaves can’t ever completely dry.
You can protect them by spraying with landscape fungicide (click for sources) when damage is first seen, usually early May.
Rake up and dispose of leaves that fall.