Dealing with Fungus Gnat Infestations for Indoor Potted Plants



Fungus gnats are a major pest insect species that annoy people as well as pose a health hazard in large numbers, as they land on everything indiscriminately and drown in cups and dishes in the sink. Fungus gnat larvae eat fungi and plant roots, and can kill your houseplants. In this video I talk about the many ways people try to deal with fungus gnats, and how almost all of them don’t work!

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38 comments

  1. I don't know what soil you bought, but Miracle Gro has some bad reviews b/c of gnats.
    I buy the Pro Mix.

  2. Nobody ever talks about how they will crawl down between the container and the soil where they separate when the soil drys and shinks because there's usually still some moisture down there and they will lay there eggs down below especially if you add rocks to the bottom of your pots for drainage. Best bet is to never get them.

  3. #1 dont overwater your plants
    #2 let the soil dry out before wateri g again
    #3 use mosquito bits; mixed with water to make a tea and water with this. Its kills the eggs and larvae

  4. Best way to get rid of gnats in house plants:
    1. Repot with new soil (even in existing pot). Throw the soil in a garbage bag and seal tightly, to dispose of eggs, larva and junior gnats in the soil.
    2. Spray roots with Garden Safe Insecticidal Soap. Make sure to spray in the remaining soil on the roots.
    3. Refill pot with new soil, making about 1.5 inches for room on the top of soil for sand.
    4. Add a thick layer of 1.5” – 2” of sand. Pat down to keep it tightly packed.
    5. Water the plant. If sand moves to expose soil, add more sand at the top.
    I tried everything and couldn’t get rid of gnats in my plants, until I tried this method with sand. This worked, no more gnats going on 2 months. Gnats can’t dig into tightly packed sand, nor can larvae or gnats crawl up through the sand if packed tightly.

  5. I had same issue with my plants.I used mosquito dunks and in two months all gone. Mesage me if any one want to know the methid of use it. Thanks

  6. HELP! SOLUTIONS TO THIS PROBLEM ?? I have the same larvae ( and the "mosquitos" it develops ), more than a year now, it was attacked ALL my plants, i have literally transplanted each of them, cleaning the pot with alcohol.. but then they appeared again. Bought new soil and re-pot again… nothing, tried home-made pesticide ( with tacabo) it didn't help, tried commercial pesticide, did not work, im fed up and so sad ! I have sooo many plants, i love them too much, and im hopeless !

  7. Those dunks worked for me and that is all I do now. I keep a couple of 1-2 lt bottles filled with water and a small piece of dunk in them. Allow for at least 24 hours before using and water your plants properly. You said it didn't work for you because the soil was "sopping wet all the time". Normal house plants should never be in sopping wet soil all the time. Also, all of my plants now have drainage holes, so they are never dry at the top with root rotting sludge on the bottom (and everything in between).

  8. They’re demonic ! Ever since an undetected leakage that provided moisture and fungus they haven’t left my apartment
    I am being terrorised by them
    I can’t have a dustbin anywhere
    I can’t put my food waste in any place even covered tightly
    They can find some place to go into a hibernation mode ! And emerge in the coldest parts of my apartment, they even can survive in a operating microwave ! Yesterday I was in a rush , I quickly put a potato in the microwave oven And after few minutes I took out my hot jacket potato and to my astonishment I saw few of them flying out of the microwave oven !
    They can live happily in sub zero temperatures and the hotter the better as far as they’re concern
    They always sit on the exact spots and they leave a very black ink like of markings when the get squatted !
    They are not just an insect
    They’re demons !

  9. Try putting garlic on top of the pot it actually works, and in 1 day there won't be any fungus gnat, believe me I've tried it

  10. They are spraying 'kemtrailing' the planet with Aluminum, Berium, and Strontium in the weather warfare. This is neutralizing the soil, rather than an acidic base and it is causing 'fungus' problems everywhere. SO it would only be logical the soil we buy today contains the same. This was never a problem in the past. The other thing is our 'water supply' to our homes contains greater amounts of bacteria. I have never seen the 'pink' rims and the smell of the 'sewage water' being fed back to us. StoptheCrimedotnet Deborah-Tevaras can give you a great deal of info on this. I have had this problem now for a few years 'knats'…it was NEVER a problem in the past. Thank you for this video I will do this. I have thought for a while the 'potting soil' I have purchased of late is very bad. THANK YOU.

  11. i've tried growing plants indoors but somehow insects always take over so I stopped keeping plants indoors (luckily, we have lots of plants outdoors). Now that I've retired and have more time, I'd like to at least try to grow ginger so I can make gari (the ginger I can get in the stores have lost their rosy spring color which I want so the gari gets that sweet pink color). I also am going to start doing sprouts again too–mung beans since I love eating those, radish/garlic/onion for their spicy hit in salads, maybe some others later. A little too often, we get notified that leafy greens have been found to have too high a level of bacterial contamination so maybe eating sprouts will allow us to have our greens and eat them too. And I want to try to grow a few of those icicle white radishes in clear plastic spaghetti pasta storage containers that I'll drill holes for drainage into–i want to watch the radish grow and I haven't seen these white radishes around since I was a child–they have the large daikon in the stores but not the finger-size white radishes that I always thought were delicious when I was a child. I don't want a lot, just a few every now and then. But I've been reluctant to grow things because of the gnats and the other pests that always seems to spontaneously generate. thank you for doing all the experimenting with how to sterilize the soil and the seeds/rhyzones. I used to "bake" coconut coil to put white worms into for the fish, back when we were breeding fish, but never thought to do that with other soil–not that baking the coil kept the pests from infesting eventually anyway.

  12. If you would have taped the entire top of pot they die off in 2 weeks…I use saran wrap,then if I want to kill flying adults just use dish soap spray with a little isopropyl.you have to cover holes on bottom of pots to.

  13. The sand seems to be a good idea to cut the fungus Gnat’s tummies up and rid my plants that I brought in. This is the first year that I could recall getting these horrible bugs on my plants as I usually replant most before any types of infestations occurs when my visiting mother in law doesn’t like to refrigerate fruits and although I shop frequently she’s got to have a lot and this spring when she was here, I had to fight fruit flies. I was thinking perhaps these might’ve had something to do with the fungus gnats. I don’t want to lose some of my plants but I think I’m in for a battle.

  14. Definitely want to steam sterilize the medium first.Yellow sticky traps to try and keep a handle on the adults and to break the life cycle,beneficial nematodes specifically for fungus gnat larve is the best bet.They are THE most tenacious little bastards.I've poured gallons of BOILING water through the soil and it looked like it killed them all but still every,time once they get established they'll come back anyway.You need to get them with something that will EAT THEM FOR DINNER!

  15. Like your setup and approach. Can ocean sand be used if it is well washed? And then i guess baked

  16. You showed your sand, diotomacious earth and sphagnum peat moss ready to go into the oven. 1 question: what ratio of the moss, earth and sand would be appropriate? Or is that dependent on the plant you're going to put in it?

  17. Burn the top layer of potting soil (i use a propane torch every other day for about a week and also put up sticky tape. Tends to kill them out for me..

  18. good lesson and explanation – I am trying the spray peroxide & water method some of my posts are very large & hard to maneuver.

  19. Hydrogen peroxide does not work, I used it on them crawling across my patio. The only thing I had yhat worked great was Vets Best Flea and Tick spray I have for my dog. Killed them instantly!

  20. You may try bacillus thuringiensis (BT) or beneficial nematodes, should this occur again. Also, I have successfully used Gnat Nix, a granular product that goes over the potting mix. A 1/2" layer of sand may also work. I think you will be fine just sterilizing the peat moss. Keep it in jumbo zipper bags or in an airtight plastic container. My current problem is with my Vermihut. Can't use anything lethal to my composting worms!

  21. Water only from the bottom dry out the top make a neem cake or meal late 80 and sprinkle on the top of the pot gets rid of them every time

  22. I'm dealing with this now. But they are comming from the drains or ventalation. Landlord doesn't want to fix leaks that have been in the house since before I moved in. So I think they are in the walls. O_o

  23. Watch the PH level when using – sphagnum peat moss. Also, sphagnum peat moss is not nutritious at all, so basically you've got a pretty sterile mix. This is a good thing for potted indoor plants but you still need to feed them. I use this soluble fertilizer and I really like it: https://amzn.to/2PxZVkT

  24. 1 part hydrogen peroxide to 3 parts water will kill all the fungus knat larvae in the soil! It will completely kill them and the eggs!

  25. I use smart pots (3 gal), as they conveniently fit perfectly into a 5 gal bucket (used to soak or feed only). I set the cloth pit in a H2O2 (3
    %) solution, diluted with filtered water (4:1). Kills gnats and root rot…let soak according to need…can't really overdo it.

    I also mix copious amounts of Diatomaceous earth into my soil…
    And use a yellow sticky trap to set near the plant base.

    Neem oil sprayed on the leaves (with lights off). I use Black Magic "soil"…and Ii let it get almost bone dry before watering. A GREAT benefit of the cloth pots, is you can dip the pot into a 5gal bucket to water or feed…and NOT wet the top layer…

    PEACE ☮️😎

    …GONE in ONE life cycle.

  26. yeah but for those of us who can't rinse out the roots and such and grow indoors with starter soil or coconut coir do you have suggestions for killing them please.

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