Why do my hydrangeas look like they have grey mould on them
the leaves of my hydrangeas look like they have a grey mold on them and some are yellowing too.
The mould that you seeing on the leaves is powdery mildew. This disease can be controlled with Yates Rose Shield, a combination insecticide fungicide product.
From your friends at Yates Gardening
Answered: 7 Apr, 2014