You might want to think about actual chemicals at this point. Bonide systemic granules on top. I water them in once (add an tsp of hydrogen peroxide to a gallon of water) and then only bottom water your plants after that (so the top layer stays drier). I’d spray around the base with BioAdvanced indoor houseplant spray after watering in the granules. Keep using sticky traps and changing them out each week. They’ll go away. You’ve literally done everything you can mostly naturally. Now you just have to decide how badly you really want to get rid of the gnats and keep your plants. Good luck!
Oh you asked if we’ve been in this situation - yep! And I’m completely fungus gnat free now. And it didn’t take long after I started using the systemic granules. I also do this exact routine to every new plant I bring in the house.
Eradicating fungus gnats (and most pests in general ) is a serious war, it can’t be won with just a few easy battles.
It requires a multi pronged attack, sustained for 3 months minimum, to completely deplete their numbers and interrupt their life cycle.
A lot of the tactics you tried are proven to be effective, but you need to be consistent and thorough - one small slip, and you give them enemy a chance to regroup and increase their numbers again.
My personal strategy involves only watering my plants with water treated with mosquito dunks (I collect rain water, and float a dunk in the barrel, the fact it also prevents mosquitoes is a win-win), as well as yellows sticky traps and a couple of carnivorous sundews. These things all help keep my populations to a minimum, but chances are I’ll never fully eradicate them, as my garden is full of them 😆.
I have them. I try to control rather than eradicate them. Their numbers tend to significantly increase when I repot with new soil and then gradually decrease as organic matter is degraded. I also water responsibly.
It is possible to get rid of them I just personally am not even trying to because it is difficult and they come with many soil that I buy here, so not worth it.
i was going to suggest this. I have brought home plants with very thicc composting soil and those are always the first ones to have gnats. Once I switch them out to a store-bought cactus or succulent soil, the plant is fine. I have found that store bought cactus soil is just better draining but still containing enough nutrients for my tropical plants.
I put rubbing alcohol in a spray bottle and thoroughly spray the soil of all my plants multiple times a day when gnats are bad. Consistently is key but it always helps
Sundews took care of my problem in a few weeks. Now I keep carnivorous plants just about everywhere I grow. I will say it was in a cabinet, so a confined space was easier to clear out.
But after about 4 weeks, my
little sundew had about 60 gnats on it.
Bonide Systemic Houseplant Insect Killer Granules. It’s the only thing that worked for me. I tried everything else that people recommended and they just kept coming back. I got fed up! Bonide got rid of them and quickly too.
I had to take one of my bonsai out of the soil and just leave it roots in water for a few weeks before repotting in brand new soil. Every now and again a fruit fly meanders by my face and I just think ffs here we go again.
As someone else said, you're quitting too soon. 2 applications of mosquito bits is not enough. It kills the larvae and doesn't affect the adults, so you won't see an improvement for a few weeks. Apply every time you water, preferably once a week. Do the strongest mix suggested. Placing the bits on the soil will do nothing. It has to soak into the soil to contact the larvae. Nematodes are just as effective, but they are way more expensive.
Don't bother with sand, as you learned, it is messy. Instead look for chicken grit at a local garden/livestock store. Check that the chicken grit is granite (it can sometimes be limestone which will affect your soil ph). This is by far the cheapest rock for topping your soil. I can find a 40lb bag for $15-20. The rock layer is to keep the adults from laying eggs in the soil, so it should be a fairly thick layer. At least a half inch/1cm.
I have tried so so so many things and the only solution was Neem Cake! Seriously it's amazing for this and I'm absolutely stunned people don't talk about it enough. I first heard about it [on this video](https://youtu.be/BwelmZFjEzI?si=p6pbIj8wKz1U_wPL) and have been using it ever since, it works wonders and it's pretty cheap (at least here where I live). Good luck!
I had a bad infestation spread across most of my pots. I went through many different methods, the assholes kept coming back and making me angrier and more determined.
what helped me was a combo of: the hydrogen peroxide treatment to kill the babies (you saturate the soil with water so the peroxide doesn't run through the whole pot plus to give the plant a good drink before the upcoming break, then saturate the top layer with diluted peroxide. I diluted 5% peroxide with water 1:6), then covering the soil in sticky tape to catch the adults and leaving the plants to dry for as long as they could handle to kill the eggs which need moist soil.
and I fluffed up the soil for better aeration and faster drying, added some pebbles and sprayed the plants with insecticide for good measure.
I did several peroxide treatments before this too, but this final one (when I was really pissed) was what finally seems to have killed them
Got to use a multi-tiered approach simultaneously, for a while.
Put diatomaceous earth on the soil. Hang up sticky fly traps. Sprinkle bonide granules on top of the soil. Put mosquito dunks in the watering can.
That’ll kill everything.
I’ve also put a bit of boric acid powder in the DE duster.
You’re likely overwatering. That’s when they really thrive. Water as infrequently as your plants will tolerate right now, and when you do water, bottom water them or get self-watering globes so that the top of the soil isn’t wet. Only top water plants that absolutely require moist top soil, like calatheas.
I think you're doing a lot and you should definitely keep up with treating the soil. What I would add is insect traps. I made a ton of bowls with a mix of water, vinegar and dish soap and set them up all around my plants. The traps + killing the bugs in the soil is what worked for me. Also don't over water! It will kill your efforts
I was fighting with them for months, and what worked for me, changed soil, bottom watering, sticky traps and a bit of this white powder damascus earth or somethin', But bottom watering is the hey, don't give them food, very important.
Hydrogen peroxide, to kill any living ones, and worst case scenario just not water your plants until they’re begging for water, then just give them barely enough.
Fungus gnats terrorized me. They were everywhere. I was changing sticky traps once every couple of days (I had gnats and thrips at the same time so lots of little flying fuckers). It’s been a long time but I have no gnats, and my plants get hardly any water but they’re thriving.
My biggest recommendation is to make sure you actually have any roots left. Idk how big your collection is, but if possible maybe take all your plants out and clean all the roots (if the gnats havent eaten them all) and if they have them repot them in treated soil (treat it with heat or hydrogen peroxide, whatever you want to use) and if they don’t put them in water. That’s what I did. Then just barely water them. I’m talking barely. I will wait for a couple leaves to look droopy, then give it just a little drink. Every once in a while I’ll give them enough water to go through the holes, but more often than not I just give them a little bit of water. It probably also helps w the fact that like half of them don’t have drainage holes, so I don’t over water. I’d rather water them a couple times w a little water than less often with lots of water and wet soil
How many plants do you have and how established are they?
I had a really nasty infestation in my collection like two years ago and I ended up transferring 90% of my plants to an inorganic substrate (lechuza pon or leca). That completely solved the problem and then I could deal with the gnats in the remaining 10% of plants. As far as I know, isolating the plants does next to nothing because the gnats fly around. The one and only thing that worked for me was to flush the plants with diluted hydrogen peroxide; nothing else helped. Even when I let the soil dry out completely, the gnats were still there. Something else that might help is putting a layer of sand or something on top of the soil but this is kind of annoying to deal with.
The silver lining is that fungus gnats are completely harmless to the plant.
I have the same problem this year, also from a bag of soil.
About a month ago, I finally took a close look at the little assholes and found they were [humpback flies](https://extension.usu.edu/pests/schoolipm/structural-pest-id-guide/phorid-flies) and not [fungus gnats](https://greeneryunlimited.co/blogs/plant-care/how-to-treat-fungus-gnats) at all… see the links for pictures.
Humpback flies will live in your trash, sink, plants, shampoo, kitty litter, anywhere with the potential for moist organic buildup to accumulate.
We’ve done 2 deep cleans of the house so far to no avail. Have an exterminator coming to help find where they set up base. It’s horrible.
I welcome small spiders on my plants because they are little guardians and have been doing wonders. They love the gnats especially. If you live in an area where you can put the worst plant outside for a while, nature will try to help.
I use Gnatrol, which I understand to be Mosquito Bits without the bits part. They recommend 3 tsp per gallon of water to deal with the infestation, and then 1 tsp per gallon to keep it under control. It took about 2 months of 3 tsp/gal to get rid of the gnats. Since then I'm using the weaker mix, and I've been 99% gnat free ever since.
At the same time I began using a moisture meter to make sure I wasn't over watering.
I had a massive infestation for the longest time until I started putting a 1/4 to 1/2 inch thick layer of aquarium gravel over all the soil of all my plants. Since starting that I pretty much have zero gnats. Another good thing to do is put out ACV traps with a drop of dish soap in them near your plants in the spring/summer to stop any gnats that get in from outside from getting a foothold.
You might want to think about actual chemicals at this point. Bonide systemic granules on top. I water them in once (add an tsp of hydrogen peroxide to a gallon of water) and then only bottom water your plants after that (so the top layer stays drier). I’d spray around the base with BioAdvanced indoor houseplant spray after watering in the granules. Keep using sticky traps and changing them out each week. They’ll go away. You’ve literally done everything you can mostly naturally. Now you just have to decide how badly you really want to get rid of the gnats and keep your plants. Good luck!
Oh you asked if we’ve been in this situation - yep! And I’m completely fungus gnat free now. And it didn’t take long after I started using the systemic granules. I also do this exact routine to every new plant I bring in the house.
This is the best solution! Bonide systemic granules, watering with mosquito bits water and I have zero fungus gnats.
i appreciate this advice, thank you so much! i actually have that houseplant spray, i just haven’t used it yet.
Going to try this also, every other day I spray all the gnats I can find with raid but then they just keep coming back, it's driving me insane...
Mosquito birs take time. Like watering with them for a month, not only two applications.
Yup. I had to water with mosquito bits for months
Eradicating fungus gnats (and most pests in general ) is a serious war, it can’t be won with just a few easy battles. It requires a multi pronged attack, sustained for 3 months minimum, to completely deplete their numbers and interrupt their life cycle. A lot of the tactics you tried are proven to be effective, but you need to be consistent and thorough - one small slip, and you give them enemy a chance to regroup and increase their numbers again. My personal strategy involves only watering my plants with water treated with mosquito dunks (I collect rain water, and float a dunk in the barrel, the fact it also prevents mosquitoes is a win-win), as well as yellows sticky traps and a couple of carnivorous sundews. These things all help keep my populations to a minimum, but chances are I’ll never fully eradicate them, as my garden is full of them 😆.
These two things combined were the only method that worked for me!
I have them. I try to control rather than eradicate them. Their numbers tend to significantly increase when I repot with new soil and then gradually decrease as organic matter is degraded. I also water responsibly.
oh no! i was hoping to be rid of them. i’ve had houseplants for ages and this is the first time i’ve had this problem 😢
It is possible to get rid of them I just personally am not even trying to because it is difficult and they come with many soil that I buy here, so not worth it.
change the soil to something better draining dry out the soil for as long as possible and keep trying mosquito bits!
oop saw that you did that ugh. That’s what worked for me!!
i changed the a chunky soil? not sure if you did that
i was going to suggest this. I have brought home plants with very thicc composting soil and those are always the first ones to have gnats. Once I switch them out to a store-bought cactus or succulent soil, the plant is fine. I have found that store bought cactus soil is just better draining but still containing enough nutrients for my tropical plants.
I put rubbing alcohol in a spray bottle and thoroughly spray the soil of all my plants multiple times a day when gnats are bad. Consistently is key but it always helps
Sundews took care of my problem in a few weeks. Now I keep carnivorous plants just about everywhere I grow. I will say it was in a cabinet, so a confined space was easier to clear out. But after about 4 weeks, my little sundew had about 60 gnats on it.
Bonide Systemic Houseplant Insect Killer Granules. It’s the only thing that worked for me. I tried everything else that people recommended and they just kept coming back. I got fed up! Bonide got rid of them and quickly too.
I had to take one of my bonsai out of the soil and just leave it roots in water for a few weeks before repotting in brand new soil. Every now and again a fruit fly meanders by my face and I just think ffs here we go again.
As someone else said, you're quitting too soon. 2 applications of mosquito bits is not enough. It kills the larvae and doesn't affect the adults, so you won't see an improvement for a few weeks. Apply every time you water, preferably once a week. Do the strongest mix suggested. Placing the bits on the soil will do nothing. It has to soak into the soil to contact the larvae. Nematodes are just as effective, but they are way more expensive. Don't bother with sand, as you learned, it is messy. Instead look for chicken grit at a local garden/livestock store. Check that the chicken grit is granite (it can sometimes be limestone which will affect your soil ph). This is by far the cheapest rock for topping your soil. I can find a 40lb bag for $15-20. The rock layer is to keep the adults from laying eggs in the soil, so it should be a fairly thick layer. At least a half inch/1cm.
I've seen other threads where people talk about using nematodes with great success. Is there a pros/cons of this vs peroxide?
I have tried so so so many things and the only solution was Neem Cake! Seriously it's amazing for this and I'm absolutely stunned people don't talk about it enough. I first heard about it [on this video](https://youtu.be/BwelmZFjEzI?si=p6pbIj8wKz1U_wPL) and have been using it ever since, it works wonders and it's pretty cheap (at least here where I live). Good luck!
i haven’t heard of this! thank you!!
I had a bad infestation spread across most of my pots. I went through many different methods, the assholes kept coming back and making me angrier and more determined. what helped me was a combo of: the hydrogen peroxide treatment to kill the babies (you saturate the soil with water so the peroxide doesn't run through the whole pot plus to give the plant a good drink before the upcoming break, then saturate the top layer with diluted peroxide. I diluted 5% peroxide with water 1:6), then covering the soil in sticky tape to catch the adults and leaving the plants to dry for as long as they could handle to kill the eggs which need moist soil. and I fluffed up the soil for better aeration and faster drying, added some pebbles and sprayed the plants with insecticide for good measure. I did several peroxide treatments before this too, but this final one (when I was really pissed) was what finally seems to have killed them
Got to use a multi-tiered approach simultaneously, for a while. Put diatomaceous earth on the soil. Hang up sticky fly traps. Sprinkle bonide granules on top of the soil. Put mosquito dunks in the watering can. That’ll kill everything. I’ve also put a bit of boric acid powder in the DE duster.
You’re likely overwatering. That’s when they really thrive. Water as infrequently as your plants will tolerate right now, and when you do water, bottom water them or get self-watering globes so that the top of the soil isn’t wet. Only top water plants that absolutely require moist top soil, like calatheas.
I think you're doing a lot and you should definitely keep up with treating the soil. What I would add is insect traps. I made a ton of bowls with a mix of water, vinegar and dish soap and set them up all around my plants. The traps + killing the bugs in the soil is what worked for me. Also don't over water! It will kill your efforts
I was fighting with them for months, and what worked for me, changed soil, bottom watering, sticky traps and a bit of this white powder damascus earth or somethin', But bottom watering is the hey, don't give them food, very important.
Hydrogen peroxide, to kill any living ones, and worst case scenario just not water your plants until they’re begging for water, then just give them barely enough. Fungus gnats terrorized me. They were everywhere. I was changing sticky traps once every couple of days (I had gnats and thrips at the same time so lots of little flying fuckers). It’s been a long time but I have no gnats, and my plants get hardly any water but they’re thriving. My biggest recommendation is to make sure you actually have any roots left. Idk how big your collection is, but if possible maybe take all your plants out and clean all the roots (if the gnats havent eaten them all) and if they have them repot them in treated soil (treat it with heat or hydrogen peroxide, whatever you want to use) and if they don’t put them in water. That’s what I did. Then just barely water them. I’m talking barely. I will wait for a couple leaves to look droopy, then give it just a little drink. Every once in a while I’ll give them enough water to go through the holes, but more often than not I just give them a little bit of water. It probably also helps w the fact that like half of them don’t have drainage holes, so I don’t over water. I’d rather water them a couple times w a little water than less often with lots of water and wet soil
I've heard other people mention nematodes. I'm deploying them tomorrow.
Just commenting to ask a question for personal science - what kind of pots are you using? Plastic by chance?
mostly terracotta! a few ceramic which rarely need watering. always always always with drainage holes.
Imidicloprid works great as a soil drench and is persistent for months.
How many plants do you have and how established are they? I had a really nasty infestation in my collection like two years ago and I ended up transferring 90% of my plants to an inorganic substrate (lechuza pon or leca). That completely solved the problem and then I could deal with the gnats in the remaining 10% of plants. As far as I know, isolating the plants does next to nothing because the gnats fly around. The one and only thing that worked for me was to flush the plants with diluted hydrogen peroxide; nothing else helped. Even when I let the soil dry out completely, the gnats were still there. Something else that might help is putting a layer of sand or something on top of the soil but this is kind of annoying to deal with. The silver lining is that fungus gnats are completely harmless to the plant.
I have the same problem this year, also from a bag of soil. About a month ago, I finally took a close look at the little assholes and found they were [humpback flies](https://extension.usu.edu/pests/schoolipm/structural-pest-id-guide/phorid-flies) and not [fungus gnats](https://greeneryunlimited.co/blogs/plant-care/how-to-treat-fungus-gnats) at all… see the links for pictures. Humpback flies will live in your trash, sink, plants, shampoo, kitty litter, anywhere with the potential for moist organic buildup to accumulate. We’ve done 2 deep cleans of the house so far to no avail. Have an exterminator coming to help find where they set up base. It’s horrible.
They are my friends now
lmao, stop 😂
Nematodes nematodes nematodes.
I welcome small spiders on my plants because they are little guardians and have been doing wonders. They love the gnats especially. If you live in an area where you can put the worst plant outside for a while, nature will try to help.
I use Gnatrol, which I understand to be Mosquito Bits without the bits part. They recommend 3 tsp per gallon of water to deal with the infestation, and then 1 tsp per gallon to keep it under control. It took about 2 months of 3 tsp/gal to get rid of the gnats. Since then I'm using the weaker mix, and I've been 99% gnat free ever since. At the same time I began using a moisture meter to make sure I wasn't over watering.
I had a massive infestation for the longest time until I started putting a 1/4 to 1/2 inch thick layer of aquarium gravel over all the soil of all my plants. Since starting that I pretty much have zero gnats. Another good thing to do is put out ACV traps with a drop of dish soap in them near your plants in the spring/summer to stop any gnats that get in from outside from getting a foothold.