Another method for dealing with Fungus Gnats is hydrogen peroxide. I read about it and thought "This is crazy!" but I was desperate enough to try anything, so I did. Mix 1 part 3% house hold peroxide with 3 parts water (or was it 4 parts? I can't remember...) and water the plants thoroughly with the mix. The soil foams and bubbles, but at the end the fungus gnats are gone, and the plant remains healthy. I have tried this with food grade 35% peroxide as well, and it does NOT work (I was diluting with 33 parts water to compensate for the higher peroxide content). I suspect the stabilizer(s) they put in household peroxide may be the active ingredient rather than the peroxide itself. As different companies use different stabilizers, this may make a huge difference...
Another method for dealing with Fungus Gnats is hydrogen peroxide. I read about it and thought "This is crazy!" but I was desperate enough to try anything, so I did. Mix 1 part 3% house hold peroxide with 3 parts water (or was it 4 parts? I can't remember...) and water the plants thoroughly with the mix. The soil foams and bubbles, but at the end the fungus gnats are gone, and the plant remains healthy. I have tried this with food grade 35% peroxide as well, and it does NOT work (I was diluting with 33 parts water to compensate for the higher peroxide content). I suspect the stabilizer(s) they put in household peroxide may be the active ingredient rather than the peroxide itself. As different companies use different stabilizers, this may make a huge difference...