Controlling Mold on Houseplant Soil: Effective Methods Beyond Charcoal

A West Coast Canadian gardener asked about using charcoal for mold control and whether replacing the top soil with sand or perlite would help.

Better Than Charcoal

1. Remove the top 1 inch of moldy soil.
2. Spray the exposed soil surface with an antifungal spray (Consan 20 or Lysol).
3. Replace with fresh, sterile potting mix.

Watering Practices to Prevent Mold

• Top‑water (not bottom‑water) so you can see when the soil is saturated.
• Allow the top 1–2 inches to dry between waterings.
• Use a well‑draining mix (add perlite/vermiculite to commercial soil).

Note on Soil Mold

Surface mold rarely harms established plants; it’s mainly a concern for seedlings (“damping off”).