brown spots on Calathea
Quick answer
If your Calathea has brown spots, the most likely cause is: Brown spots on Calathea leaves indicate pathogen infection with two primary patterns. BACTERIAL SPOT (Pseudomonas, Xanthomonas): Angular brown lesions with yellow halos bounded by leaf veins, creating geometric patterns. Spots feel water-soaked and may ooze bacteria in humid conditions. FUNGAL ANTHRACNOSE (Colletotrichum, Myrothecium): Circular or irregular brown spots with concentric rings, often starting at leaf margins or where water pools. Both pathogens thrive when leaves remain wet 4+ hours combined with poor air circulation.
Start here:
- 1. Isolate immediately to prevent spread to nearby plants
- 2. Remove severely infected leaves at base with sterile scissors (wipe with 70% alcohol between cuts)
Why Calathea gets brown spots
Goeppertia spp.
Brown spots on Calathea leaves indicate pathogen infection with two primary patterns. BACTERIAL SPOT (Pseudomonas, Xanthomonas): Angular brown lesions with yellow halos bounded by leaf veins, creating geometric patterns. Spots feel water-soaked and may ooze bacteria in humid conditions. FUNGAL ANTHRACNOSE (Colletotrichum, Myrothecium): Circular or irregular brown spots with concentric rings, often starting at leaf margins or where water pools. Both pathogens thrive when leaves remain wet 4+ hours combined with poor air circulation.
How to reverse brown spots on Calathea
- 1
Isolate immediately to prevent spread to nearby plants
- 2
Remove severely infected leaves at base with sterile scissors (wipe with 70% alcohol between cuts)
- 3
Apply copper-based fungicide/bactericide weekly for 3-4 weeks following label instructions
- 4
Improve air circulation with oscillating fan 3-4 feet away on low setting
- 5
Water at soil level ONLY—never splash leaves or mist during treatment
- 6
Switch to bottom-watering to keep foliage completely dry
Keep brown spots off this Calathea
Never mist Calathea leaves—use humidifiers or pebble trays for humidity instead. Water early morning at soil level only. Maintain 60-80% ambient humidity with good air circulation. Sterilize pruning tools before each use. Quarantine new plants for 14 days before introducing to collection.