Gardenia Problem

As an evergreen shrub, it is normal for older leaves of a gardenia to turn yellow and drop. This typically occurs during early spring before new growth appears.
If chlorosis (leaf yellowing with veins still green) is present now or occurs at other times of the year and there is no evidence of insect pests or disease, there may be an environmental or cultural factor causing yellow foliage. Gardenias are acid-loving plants that grow best in a acid (low pH) soil. Iron is an essential nutrient and if the soil pH is above 7.0, the iron may be in a form that is not available to the plant. It may be necessary to apply iron if the leaves are chlorotic, but in the long run, it’s good to know that there are fertilizers made specifically for acid loving plants like these.