Powdery Mildew on Houseplants: Identification, Prevention & Treatment

What Is Powdery Mildew?

A fungal disease caused by several species, appearing as a grayish-white powdery coating on leaves, stems, and flowers. It thrives in high humidity with poor air circulation. Common targets: grape ivy, begonias, African violets.

Damage & Symptoms

The fungus kills leaf tissue underneath, leading to yellowing, leaf drop, stunted growth, and general decline.

Immediate Actions

• Remove all infected leaves and fallen debris.
• Move plant to a less humid spot with better airflow.
• Keep foliage dry—water at the base, not overhead.

Treatment Options

Commercial fungicide: Follow label directions.
Homemade remedy: Mix 1 tablespoon baking soda + 1 teaspoon mineral oil (or horticultural oil) in 1 quart water. Shake well and spray all plant surfaces weekly until resolved.

Prevention

• Space plants for air movement.
• Avoid wetting leaves.
• Reduce humidity if chronically high.
• Inspect new plants before introducing them.