Comprehensive Fungus Gnat Management: Dry Soil and Soil Removal

Duplicate question on fungus gnats. Expert provides detailed integrated approach.

Root Cause

Larvae live in top 2 inches of soil, feeding on decaying organic matter and rotting roots.

Step-by-Step Eradication

1. Remove loose surface soil not touching roots – discard (contains most larvae).
2. Dry soil deeply – just short of wilting. Top inch bone dry kills larvae.
3. Water minimally – only enough to re-dry in a week or less.
4. Wait out adults – they die in ~1 week. Population declines gradually.

Prevention

• Never repot unnecessarily.
• Use sterile soilless mixes.
• Avoid water-retentive additives ("moisture control").