Q: Some of my Gardenia bushes have yellow leaves. Is this an iron deficiency ? What do you recommend ?
A: It is common in spring to see yellow leaves on gardenia, holly and Southern magnolia. The phenomenon is caused by the plant moving food resources out to new growth on the branch tips, leaving interior leaves to survive as best they can.
The weakened yellow leaves may get spots from fungi taking advantage of them but the disease rarely moves to other parts of the plant.
If the yellow leaves are several inches back from the branch tips, and if the tip leaves are green, your plant is reacting normally. It will look fine in a few weeks. Spraying with fungicide or fertilizing will not help the situation, it’s just a part of the lifecycle of the plant.