brown spots on Chinese Evergreen
Quick answer
If your Chinese Evergreen has brown spots, the most likely cause is: Brown spots on Aglaonema are primarily driven by two factors: 1) Cryptic pests like thrips and spider mites, which feed on sap and create necrotic lesions often camouflaged by leaf variegation; 2) Edema and fungal pathogens (Pythium) resulting from peat-heavy soils (e.g., standard Miracle-Gro) that retain excessive moisture at the root zone, causing cell rupture and localized browning.
Start here:
- 1. Pest Inspection: Use a flashlight to check leaf undersides and crevices for tiny white/yellow larvae (thrips) or fine webbing (mites); treat with neem oil or insecticidal soap every 7 days for 3 weeks.
- 2. Soil Audit: If spots are mushy or spreading, unpot and perform a bare-root rinse; remove all old peat-heavy soil and repot in a chunky aroid mix (50% soil, 30% perlite, 20% bark).
Why Chinese Evergreen gets brown spots
Aglaonema spp.
Brown spots on Aglaonema are primarily driven by two factors: 1) Cryptic pests like thrips and spider mites, which feed on sap and create necrotic lesions often camouflaged by leaf variegation; 2) Edema and fungal pathogens (Pythium) resulting from peat-heavy soils (e.g., standard Miracle-Gro) that retain excessive moisture at the root zone, causing cell rupture and localized browning.
Other documented causes on chinese evergreen:
- • Brown spots on Chinese Evergreen emerge from two primary mechanisms. EDEMA/CELLULAR RUPTURE: When overwatering coincides with high humidity (>70%), leaf cells absorb water faster than transpiration can release it, causing cellular burst that appears as water-soaked brown patches, often with yellow halos. FLUORIDE/SALT TOXICITY: Aglaonema is particularly sensitive to fluoride and mineral salts commonly found in tap water and fertilizer; accumulation at leaf margins and tips causes necrotic brown tissue. The thick, waxy cuticle makes leaves susceptible to edema because it limits rapid water vapor exchange.
How to reverse brown spots on Chinese Evergreen
- 1
Pest Inspection: Use a flashlight to check leaf undersides and crevices for tiny white/yellow larvae (thrips) or fine webbing (mites); treat with neem oil or insecticidal soap every 7 days for 3 weeks.
- 2
Soil Audit: If spots are mushy or spreading, unpot and perform a bare-root rinse; remove all old peat-heavy soil and repot in a chunky aroid mix (50% soil, 30% perlite, 20% bark).
- 3
Humidity Boost: If spots are dry and brittle at the edges, increase ambient humidity to 50-60% via pebble trays or humidifiers.
- 4
Water Quality: Switch to filtered or rainwater to eliminate fluoride sensitivity, which can manifest as brown spotting on sheaths and leaf margins.
Keep brown spots off this Chinese Evergreen
Quarantine new nursery plants for 14 days; maintain 50-60% humidity; use aerated potting media; avoid direct leaf misting which can spread bacterial spots; weekly underside inspections.