Fungus gnats are tiny black flies that hover around the soil surface and love damp conditions. While the adults are mostly a nuisance, their larvae feed on organic matter and can damage tender roots if populations get too high. Nearly every indoor gardener will run into them, but the good news is that they are very treatable with a few easy adjustments. By targeting both the flying adults and the larvae in the soil, you can break the cycle and protect your plants
Here are some steps to reduce or eliminate Fungus gnats.
1. Inspect and Isolate
Look for small black flies near soil or on windows, and check the top layer of soil for tiny larvae. Keep infested plants away from others until under control.
2. Dry Out Soil
Allow the top 1–2 inches of soil to dry before watering again. Fungus gnat larvae thrive in constantly moist soil.
3. Sticky Traps
Place yellow sticky traps near the soil surface to catch flying adults and reduce breeding.
4. Soil Treatment
Use a diluted hydrogen peroxide solution (1 part peroxide to 4 parts water) or beneficial bacteria like Bacillus thuringiensis israelensis (BTI) to kill larvae in the soil.
5. Repot if Needed
For severe infestations, gently remove old soil, rinse roots, and repot in fresh, sterile potting mix.
6. Stay Consistent
Check weekly and refresh sticky traps as needed. With patience and adjustments to watering, fungus gnats will fade and your plants will stay healthy.