Why Are Bottom Leaves on My Outside Gardenia Turning Black?
Why are the bottom leaves of my outside gardenia turning black? We live in central FL.
Certified GKH Gardening Expert
Is it a black that rubs off? If this is the case, then this is sooty mold. It is a byproduct of a pest invasion. Sooty mold grows on the honeydew of several different pests. Treat the plants with both a fungicide (to kill the sooty mold) and a pesticide (to kill the pest).