Black Spots on Cymbidiums: Humidity Management and Fungicide

Cause: High Humidity + Wet Potting Mix

Black spots on Cymbidium leaves (especially undersides) indicate fungal infection favored by high humidity. Wet potting mix increases humidity around lower leaves.

Immediate Actions

• Reduce watering; let mix dry more between waterings.
• Increase air movement around plants.
• Spray copper-based fungicide weekly on leaves (avoid flowers/buds).
• Green copper residue on leaves extends protection.

Long-Term Fix

Repot in medium-grade orchid mix after flowering. Faster-drying mix lowers humidity at root zone and leaf bases.