Q.hydrangeas
What makes the leaves turn black? (not all of them, just some leaves are totally black) What can I do about it?
Certified GKH Gardening Expert
This appears to be either fungal or bacterial. I have a method that is all natural and safe for all plants. If you do not have, or can't get, all the ingredients, then it is ok. This is a very overbearing Pesticide/fungicide, and even though is safe for use at any time, and whenever you would like, it is still more than needs to be done. I would highly recommend not substituting the Dolomitic lime or wettable sulfur, as these are first defense. The recipe is as follows: Common Answers
First, you will want to prime the ground with dolomitic lime, then spread wettable sulfur to Kill off any infection in the soil. I Also like to spray the plant itself. Mix a few drops of one or more of these ingredients into warm water with a spoonful of coconut oil: Rosemary oil, lavender oil, neem oil, garlic oil, cinnamon extract/oil and for really bad cases, also add clove oil.