How to get rid of fungus gnats without changing the soil
Fungus gnats usually arrive hidden inside fresh potting soil and keep coming back if the underlying infestation isn't treated at the root. People try to avoid repotting every plant again because handling all that soil is what caused the problem initially and risks damaging fragile flowers.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Using a light trap near the plant area
- 2Spraying the top of the soil with a liquid insecticide or hydrogen peroxide solution
- 3Using mosquito bits or watering with BTI tea
- 4Applying diatomaceous earth and neem oil
- 5Keeping soil dry and stopping overwatering
- 6Sprinkling turmeric around the plant
- 7Picking off bugs manually and spraying with a hose
- 8Watering soil with a hydrogen peroxide and water mixture
- 9Hydrating indoor soil with boiling water before use to sterilize it
- 10repotting the plant to search for and remove the bugs
- 11letting the soil dry out to kill them off
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“Unfortunately I repotted over half of my plants recently and the soil I used contained gnats so almost all of my plants have them now:(.”source ↗
“What is the best/safest way?”source ↗
“I would prefer to not replace all of the soil as that’s what caused the infestation to begin with.”source ↗
“But they keep coming back; when you hit the pot on the ground a few times, the flowers fall down.”source ↗
“Instead of mosquitoes, something about the size of a small insect is coming out from under the flowerpot.”source ↗
“i adore bugs but this is an indoor plant near a bed so im not a fan of this.”source ↗
“I recently took her out of her watering pot, to inspect her of any problems and i noticed 3 or 4 little centipede looking guys in there.”source ↗
“Is there a way to get rid of them that doesn't damage the plant? Should i repot her to look for more of theese things?”source ↗
“What should I do to get rid of the insects?”source ↗
Where this came up
People with this problem also raised
- 5Why do restaurant fly lights and cleaning fail to stop flies?
- 11How to get rid of tiny flying bugs coming out of wooden furniture
- 6Why won't house ants go away no matter what I spray?
- 3Ant infestation in my car - How to get rid of them ?
- 5Why does my house smell like cat urine when there is no visible mess?
- 2How to naturally deter bugs without harming kids