36+ Hydrangea Turning Brown. If you use too much. Another reason your hydrangea leaves are turning brown could be a fungal infection.
Many hydrangea problems can occur if plants aren't receiving enough water.
Yellow leaves on mandevilla reasons for yellow mandevilla leaves or this one. They should be in an area that isn't full sun. A problem many people have is there hydrangea leaves wilting and turning brown. Water these shrubs deeply every few days in the heat of the summer (note that hydrangea paniculata varieties do better in full sun but they can brown if they've dried out in between waterings, or if the flowers are getting hit with.