Hydrangea Sudden Leaf Browning: Fungus vs. Overwatering

Quick Field Diagnosis

Mature hydrangea with sudden brown curling leaves; 20 ft away, smaller bush showing same:

• Purple margin around brown? → Fungal leaf spot (Cercospora, Phyllosticta).
• No purple margin? → Likely overwatering/poor drainage.

Immediate Actions

1. Remove and destroy brown leaves.
2. If fungal: monitor closely—can progress fast in wet weather.
3. If overwatering: reduce irrigation immediately.

Why Speed Matters

Fungal leaf spots on hydrangeas can defoliate rapidly in humid conditions. Early leaf removal + reduced moisture slows spread. Good luck—keep monitoring.