Gardenia Yellowing Leaves: Whiteflies, Aphids, or Overwatering

Top Three Causes

1. Whiteflies: Tiny white insects on leaf undersides. Suck sap → yellow leaves.
2. Aphids: Cluster on new growth. Same damage.
3. Overwatering / poor drainage: Roots suffocate → yellowing.

Action Steps

• Inspect leaf undersides for insects.
• Test soil pH—gardenias need acidic (5.0–6.0), high organic matter.
• Adjust watering: moist, not soggy.
• Treat pests with neem oil or insecticidal soap.