The curling leaves could be a range of things GG. The most likely reason would be aphids. Check carefully underneath the leaves and if any are found then use a soap solution to eliminate them. It could also be a lack of water as hydrangeas really suck up water. OR It may be too much sun - you may need to move your plant to a more shaded position in the garden. Lastly it could be due to there not being enough potassium in the soil. A good tomato feed would rectify this problem. Good luck and I hope you find the cause soon.
Thanks Eileen, it could be the sun. I'll try the tomato food though I've used a mix for acid-loving plants. Unfortunately I don't have a very shady spot in my yard. I may have to resort to the greenhouse.
Are curled leaves the young tender ones? Look for spider mites and some fine webbing as well, if that is the case. Look careful, as they are difficult to spot and smaller than aphids. Repeat any organic treatments, as eggs will hatch. Hydrangeas don't do well in the heat of the day sun and show signs of drooping as if lacking water, but bounce back in the evening. Morning foliage will be perky too if getting enough water. Ron
Thanks Ron; I'll inspect them carefully. It does seem to be the new young leaves affected. I'll continue spraying with insecticidal soap.
