My hydrangeas have flowered well but has not been very leafy this year. The leaves are lush green for a short time, then turn grey, then black and drop off. When I cleaned up the black leaves and dead-headed, the cycle started again. I’ve never seen the leaves go grey before. It seems a bad sign. Is there anything I can do about it? I have several different types of hydrangeas growing alongside each other.

Hi Lisa, this looks like powdery mildew on the leaves which is common in spring and autumn, it is reducing the amount of chlorophyll (green pigment in plants) the plant can produce. You can control it by spraying with a suitable fungicide, which will require repeat sprays, your local garden centre will be able to recommend a suitable spray. Some home gardeners suggest spraying 1 teaspoon of bicarbonate of soda mixed in 1 litre of water with a dash of liquid soap, spray the foliage thoroughly, this helps keep powdery mildew at bay. But the best way to control it is to keep your plants well watered, fertilised and actively growing throughout the growing season, especially in the hotter months of the year. Avoid overhead watering, water the soil, not the foliage. Collect up fallen leaves and any prunings, dispose of in the rubbish or burn rather than composting the clippings to avoid spreading the disease. Try and improve air circulation around the plants by thinning out the foliage and dead heading once flowering has finished. There are some varieties that are more susceptible to disease, select disease resistant varieties. Lianne