How to Get Rid of Fungus Gnats
Direct Answer
Let the soil dry out completely between waterings — this kills larvae and prevents egg-laying. For immediate results, use yellow sticky traps to catch adults and a hydrogen peroxide soil drench (1 part 3% H₂O₂ to 4 parts water) to kill larvae. Most infestations clear within 2-3 weeks.
5 Proven Methods
- 1.Dry out the soil — Fungus gnat larvae need moisture. Let soil dry completely between waterings to break the lifecycle.
- 2.Yellow sticky traps — Place near affected plants to catch flying adults and monitor infestation severity.
- 3.Hydrogen peroxide drench — Mix 1:4 ratio of 3% H₂O₂ to water and water your plant with it. It kills larvae on contact without harming roots.
- 4.Sand or gravel top layer — A ½-inch layer of coarse sand or perlite on topsoil prevents adults from laying eggs.
- 5.Bacillus thuringiensis (BTi) — Mosquito dunks contain BTi bacteria that kill fungus gnat larvae. Soak a dunk in water and use it to water your plants.
Related Answers
Frequently Asked Questions
Adult fungus gnats are mostly just annoying — they don't damage plants. However, their larvae feed on organic matter in the soil and can damage fine roots, especially in seedlings and young plants. Large infestations can stress mature plants.
Fungus gnats typically arrive in contaminated potting soil or fly in from outdoors. They lay eggs in moist topsoil, and the larvae feed on fungi and decaying organic matter. Overwatered plants create ideal breeding conditions.
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