What causes a gardenia leaves to turn yellow and ends up having very few leaves on the bush?

lack of nitrogen and to much acid in the soil, try a little lime around the base and feed with a high nitrogen fertilizer.
What causes a gardenia leaves to turn yellow and ends up having very few leaves on the bush?
lack of nitrogen is what causes the leaves to turn yellow, which would also stunt the production of new growth. Go to your garden store and by a nitrogen enriching soil treatment.
Reply:It sounds like too much water to me.
Reply:Lessen the water and give it some iron. And check the stems for scale. Littlte white bugs.
Reply:When gardenia leaves turn yellow, the plant is lacking in phosphorus.