Oh, are there black spots? Don't worry, though, because caring for hydrangeas is really easy! I'm pretty sure it's a fungus that's causing your hydrangeas to look a little worse for wear. Don't fret, though! You can treat it in the affected area with a fungicide containing chlorothalonil, mancozeb, or thiophanate-methyl, and spray it on every 10-14 days. For an extra boost, you can add neem oil mixed with water and spray it on the spots.