I have two Rose of Sharon bushes [out of 15] that have total yellow leaves. It is fall here and unsure if to cut back or what. No signs of "bugs." They started this about 3 months ago. Thank you.
Rose of Sharon
Certified GKH Gardening Expert
If there are no bugs on the plants, the most likely explanations for yellow leaves are excessive water or a lack of nutrients in the soil. See this article for advice: