How to Get Rid of Mold on Plants in the Grow Room

Getting rid of mold on plants in a grow room requires a mix of immediate treatment, environmental control, and preventive measures. Mold can damage or kill your plants and spread quickly if not addressed.

Step 1: Identify the Type of Mold

Common grow room molds:

Powdery mildew - white, dusty coating on leaves.

Botrytis (gray mold) - fuzzy gray mold, often starts on buds or stems.

Sooty mold - dark, sticky mold growing on honeydew from pests.

Step 2: Isolate Affected Plants

Remove infected plants (or parts) from the rest of the grow area.

Prune off moldy leaves, stems, or buds using sterile scissors.

Dispose of waste in sealed bags outside the grow room.

Step 3: Apply Safe Mold Treatments

Use plant-safe antifungal agents:

Neem Oil Spray

Mix 1–2 tablespoons per gallon of water.

Spray on leaves (top and underside) every few days.

Baking Soda Spray (for powdery mildew)

1 tablespoon baking soda + ½ teaspoon liquid soap + 1 gallon water.

Hydrogen Peroxide (3%)

Dilute 1 part H₂O₂ to 3 parts water.

Spray lightly — avoid root contact.

Commercial Organic Fungicides

Like Serenade®, Trifecta Crop Control®, or GreenCure®.

Test on a small leaf first to avoid plant burn.

Step 4: Improve Grow Room Conditions

Mold thrives in warm, humid, stagnant environments.

Humidity: Keep at 40–60% (lower for flowering stage).

Temperature: Maintain 70–80°F (21–27°C).

Airflow: Use oscillating fans for constant air movement.

Dehumidifier: Run a grow room dehumidifier to reduce moisture buildup.

Ventilation: Ensure proper intake and exhaust systems are in place.

Step 5: Prevent Future Mold

Don’t overcrowd plants — ensure air can flow between them.

Water plants only at the base, not on leaves.

Sterilize tools between uses.

Use HEPA filters in air intakes.

Add beneficial microbes (like Bacillus subtilis) to the soil as a natural mold deterrent.