|One of my in-the-ground hibiscus has something bothering it. I noticed the leaves turning yellow and browning on the edges. The leaves have started dropping and are looking even worse. I turned one of the worst leaves over and noticed a small black, sooty-looking patch at the base of the leaf where it joins the stem. Any ideas on what this is and how to treat it would be greatly appreciated.
|The sooty looking patch is not the problem. It is just a sooty mold growing on a patch of sweet honeydew on the plant surface.
Yellowing leaves on hibiscus is usually due to either over or under watering. Even a brief period of soggy soil can result in root damage and yellowing leaves. Low fertility levels in the soil may also result in yellowing of older leaves of hibiscus. When growth resumes in spring, start feeding the plants periodically and keep them moist but not soggy.
Good luck with your hibiscus!