White Mold on Houseplant Soil: Causes and Solutions

White Mold on Houseplant Soil: Causes and Solutions

Finding a white, fuzzy growth on your geranium's soil surface? It's likely mold—a common issue caused by overly moist conditions. Here's why it happens and how to eliminate it.

What Causes Soil Mold?

Mold spores are everywhere in the air. They flourish when potting soil stays consistently wet, especially in warm, low-light environments. Overwatering, poor drainage, or heavy, moisture-retentive soil mixes create ideal conditions.

Effective Treatment

1. Dry out the soil: Allow the top 1–2 inches to dry completely between waterings. This breaks the mold's life cycle.
2. Apply Lysol spray: Lightly mist the soil surface with Lysol (or similar disinfectant) to kill active spores.
3. Improve conditions: Move the plant to a sunnier spot—mold struggles in bright light. Ensure the pot has drainage holes and empty the saucer after watering.

Prevention Tips

• Water only when the soil feels dry at knuckle depth.
• Use a well-draining potting mix amended with perlite.
• Provide good air circulation around plants.

Geraniums prefer drier conditions anyway, so correcting the watering routine benefits the plant overall.

Expert advice from Darlene, houseplant specialist.