89% confidence Based on 20,000+ analyzed cases

Brown-Spots on calathea

calathea with brown-spots

What's Happening

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 Fix It

  1. 1

    Isolate immediately to prevent spread to nearby plants

  2. 2

    Remove severely infected leaves at base with sterile scissors (wipe with 70% alcohol between cuts)

  3. 3

    Apply copper-based fungicide/bactericide weekly for 3-4 weeks following label instructions

  4. 4

    Improve air circulation with oscillating fan 3-4 feet away on low setting

  5. 5

    Water at soil level ONLY—never splash leaves or mist during treatment

  6. 6

    Switch to bottom-watering to keep foliage completely dry

How to Prevent It

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.

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Frequently Asked Questions

What causes brown-spots on my plant?
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...
How do I fix brown-spots?
Isolate immediately to prevent spread to nearby plants. Remove severely infected leaves at base with sterile scissors (wipe with 70% alcohol between cuts).
How do I prevent brown-spots from happening again?
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 t...