I have a beautiful hibiscus tree that is probably 12 to 15 years old and doing well. However, the past two years the flowers have become less and less. Also, I noted more yellowish leaves (iron depletion?). I am not sure what to use to get this tree in better shape. The tree receives full sun and is watered 3 times a week now.
Certified GKH Gardening Expert
Yellow leave can indicate that there is an iron issue, but I would think that overall the plant likely just needs some general fertilizer. If possible, have the soil at the base of the plant tested and then, if the test confirms a nutrient deficiency, add some balanced organic or chemical fertilizer to the soil as far out as the drip line of the plant.
These articles should help: