How do I deal with fungus gnats? I've had SO many suggestions.

[HyTymes]

This is my 4th grow and first time getting fungus gnats. I've tried letting the soil dry up it's barely "moist" knuckle deep at this point but I don't want to under water them.

I've tried crushed eggshells on top of the soil.
I've tried fruit fly traps with apple cider vinegar.
I've tried spraying the soil and leaves down with diluted alcohol spray.
I have fans blowing on them.

I'm growing auto-flowers and I'd say they're almost halfway done. Are these things going to kill my plants? How do I get rid of them?

I am new to growing but one of the responses I got when I asked was to use Mosquito Bits. I ordered them on Amazon and have not used them yet. I only have a few gnats here and there but I don't want it to get out of control.

 

[Wuddup_B]

Microblift mosquito control bti and yellow sticky traps. Daughter had a fungus gnat farm in her room from her garden and pets so I have to stay on those little turds when they make it upstairs

 

[Eledin]

cheaper alternatives will not work as well as T Drops. I have experience with multiple products and if you don’t drop the coin for Tanlin (T Drops) you won’t get the results your looking for.

Diatomaceous earth does work... and its cheap as hell, who said it doesnt work? When you mix it with the top layer of soil youre killing ALL the larvae and eggs and for the adults is a matter of time aswell, they live on the substrate even if they fly away thats where they come back to reproduce. That said if you have another pot close by with substrate that youre not using theyre just gonna move there until they can return to your tent. If DE doesnt work for you guys, youre doing something wrong. Years ago I had a really bad one, tried spraying the fuckers with neem oil, potassic soap, hydrogen peroxide and even alcohol at some point, needless to say the plants were begging me to stop... then I used diatomaceous earth, took me a couple of tries but when you get the hang of it is super easy and the cheapest option and it also benefits the plants, its not just a pest control product. I had a pot with arlite in it, I found that the fuckers went to the arlite pot while thay waited to re-colonize my substrate, just keep away anything that can serve them as a home and with DE you dont need anything else...
EDIT: As for outdoors it will prevent any non-flying insect from getting into your plants. Outdoors you will never get rid of them you can only control them, they have plenty of other places to reproduce and come back but diatomaceous earth will 100% prevent them from putting larvae in your soul to munch on your roots.
IMPORTANT: I said it already but its really important to cover any crack in the soil, specially on the sides of the pot, they can live on the sides by going deeper if you dont cover everything well, thats where most people fail with DE, if you leave them a couple of inches of space is enough for them. One single female con put up to 200 eggs (thats why it can get out of control very quickly indoors), even tho not all of them make it to adults but you can see why it wont work if you dont cover everything well. Or if you just sprinkle it on top, you need to mix it with the top layer of the soil covering EVERYTHING. I put extra on the sides cause I use textile pots and its very easy for cracks to form on the sides.

 

[Redneckx]

Dry out soil, mix with diatomaceous earth then add again a handful to the top layer and mix it in. Solved all my gnat issues once and for all and it helps with silica uptake…win/win

This is a simple solution solved with the combination of Entonem [nematodes] & yellow sticky strips.
This is a failproof and chemical free solution with no harm to flowering plants.
Do not spray oil based insecticides in flower.

I got the same problems as growth and also half done in flower but don't have any flies yet. But much larves which will not disappear just through to drought the soil out. I still use neemoil as drench not spray for sure, in hope that it helps.
Thought about using baking powder, read that should do it's job..but I'm concerned about using it but what I don't want is a fking mess In my anyway too full tent!

 

[GGOGZin]

So I can see it’s been mentioned over and over, but the easiest method would really be the Diatomaceous Earth when your soil is dry and leave for a day, hang yellow sticky traps below the canopy level to catch any adults and the DE will dry out the larvae. It’s fossilized phytoplankton and is sharp as hell under a microscope, just not able to harm us or our skin. It pierces the exoskeleton of the larvae and dries them out killing them. As was also mentioned it also contains silica which helps your plants become stronger. DE is also food grade so is 100% safe for your plants. Spinosad is effective but I only use products like that in veg, not flower as it can be absorbed by the flowers and although it’s technically safe to some extent, it could potentially ruin the taste of your finished bud.

If you need something with spinosad for veg Captain Jacks Dead Bug works wonders and deals with a huge variety of pests. For flower id avoid it, latest use being the first couple of weeks after flip.

Fungus gnats are actually pretty easy to get rid of it’s just building healthy habits and routines you need to get them gone now. Don’t water so much.

 

[Oldman13]

I am new to growing but one of the responses I got when I asked was to use Mosquito Bits. I ordered them on Amazon and have not used them yet. I only have a few gnats here and there but I don't want it to get out of control.

I found Epsom salt works quite well But doesn't happen overnight !
And if you're magnesium deficient it will fix it as well.
but another thing that works supposedly even better is a mixture of hydrogen peroxide deluded with waterkills them gnat fly larva instantly when it hits them blows apart there bodies,little soft wormy structures just can't take peroxide when it hits them
and when it stops bubbling it turns into an oxygen molecule and dissipates into the soil putting oxygen to your roots ..
diatomishes Earth apparently works but once you wet it's kind of no good anymore until It dries out
and just takes to long But at the moment I do have food grade diatomaceous earth on my soil for about 2 weeks but it hasn't worked yet and due to uncontrollable circumstances !I can't use peroxide or Epsom salt apparently My wife is allergic to Epsom salt!
She hasn't always been but apparently now she is and I think it warped her brain because she also doesn't want me to use the peroxide And since I use RO water is getting very hard to cultivate when you can't put magnesium oxide / Epsom salt to replenish the magnesium besides the coconut coir also prevents magnesium getting to your plants

 

[GGOGZin]

I found Epsom salt works quite well But doesn't happen overnight !
And if you're magnesium deficient it will fix it as well.
but another thing that works supposedly even better is a mixture of hydrogen peroxide deluded with waterkills them gnat fly larva instantly when it hits them blows apart there bodies,little soft wormy structures just can't take peroxide when it hits them
and when it stops bubbling it turns into an oxygen molecule and dissipates into the soil putting oxygen to your roots ..
diatomishes Earth apparently works but once you wet it's kind of no good anymore until It dries out
and just takes to long But at the moment I do have food grade diatomaceous earth on my soil for about 2 weeks but it hasn't worked yet and due to uncontrollable circumstances !I can't use peroxide or Epsom salt apparently My wife is allergic to Epsom salt!
She hasn't always been but apparently now she is and I think it warped her brain because she also doesn't want me to use the peroxide And since I use RO water is getting very hard to cultivate when you can't put magnesium oxide / Epsom salt to replenish the magnesium besides the coconut coir also prevents magnesium getting to your plants

Starve them of water for a day or 2 more than usual when applying DE and make sure your soil isn’t staying moist too long, that’s what they love (fungus gnats)

How long is your dry out time?

 

[Oldman13]

Starve them of water for a day or 2 more than usual when applying DE and make sure your soil isn’t staying moist too long, that’s what they love (fungus gnats)

How long is your dry out time?

It depends on which plant because of the size,
And I don't have a lot of room so I grow in plastic pots until they're decent size and then the switch to three and five gallon grow bags of a felt consistency So the plastic containers dry off very quick cuz they're small 1 gallon and the grow bags about 3 days depending So because of my multi sizes I'm kind of down there a lot and I just recently about a month ago started getting the naps right before winter starting to set in
My soil is 50/50 Happy frog and coconut coir chunks I was going two to one two scoops of happy frog and one scoop of coconut chunks but now I just went back at 50/50 And since I have to use t5 fluorescent It makes things a bit harder to deal with as well

 

[Oldman13]

I am new to growing but one of the responses I got when I asked was to use Mosquito Bits. I ordered them on Amazon and have not used them yet. I only have a few gnats here and there but I don't want it to get out of control.

Chemical base poisons i try to stay away from I used to use gnat nix And when he didn't supply anymore they suggested I use those mosquito things but sounds like chemicals to me so I stay away...
Cinnamon in your soil kills the fungus at the gnats like to eat but gnat nix It's like covering the top of your soil with the eggshells but better because your little crumbs of like white abrasive non absorbent material preventing them from digging into this oil to lay their eggs

 

[Oldman13]

Chemical base poisons i try to stay away from I used to use gnat nix And when he didn't supply anymore they suggested I use those mosquito things but sounds like chemicals to me so I stay away...
Cinnamon in your soil kills the fungus at the gnats like to eat but gnat nix It's like covering the top of your soil with the eggshells but better because your little crumbs of like white abrasive non absorbent material preventing them from digging into this oil to lay their eggs

Please excuse my typos

 

[GGOGZin]

It depends on which plant because of the size,
And I don't have a lot of room so I grow in plastic pots until they're decent size and then the switch to three and five gallon grow bags of a felt consistency So the plastic containers dry off very quick cuz they're small 1 gallon and the grow bags about 3 days depending So because of my multi sizes I'm kind of down there a lot and I just recently about a month ago started getting the naps right before winter starting to set in
My soil is 50/50 Happy frog and coconut coir chunks I was going two to one two scoops of happy frog and one scoop of coconut chunks but now I just went back at 50/50 And since I have to use t5 fluorescent It makes things a bit harder to deal with as well

Yeah I think consistency with drying out your soil mix and some DE will be your best bud in this case and don’t underestimate the power of the YELLOW sticky trap

 

[GGOGZin]

Chemical base poisons i try to stay away from I used to use gnat nix And when he didn't supply anymore they suggested I use those mosquito things but sounds like chemicals to me so I stay away...
Cinnamon in your soil kills the fungus at the gnats like to eat but gnat nix It's like covering the top of your soil with the eggshells but better because your little crumbs of like white abrasive non absorbent material preventing them from digging into this oil to lay their eggs

I second the no chemicals, I try to do only organic

Cinnamon is something I’ll have to look into more for future appreciate that

 

[DR.PNW]

I got the same problems as growth and also half done in flower but don't have any flies yet. But much larves which will not disappear just through to drought the soil out. I still use neemoil as drench not spray for sure, in hope that it helps.
Thought about using baking powder, read that should do it's job..but I'm concerned about using it but what I don't want is a fking mess In my anyway too full tent!

Baking powder, or soda, will spike your soil pH to high levels.
This will most likely shock your plants and make certain nutrients unavailable to the plants due to pH uptake requirements of each nutrient.
If a powder is to be used, diatomatious earth is the one. It is crushed diatomes, witch are essentially microscopic seashells, which will break the insects epidermis causing them to dry out and die off. It is pH neutral, and offered a natural slow-release of silica.
Neem oil is excellent, but as you mention, should not be used on flowers. Root drench is okay in small doses during flower, but also will be detrimental to beneficial nematodes if you are using them. Diatomacious earth will also negativly impact nematodes.

 

[Redneckx]

Yeah I think consistency with drying out your soil mix and some DE will be your best bud in this case and don’t underestimate the power of the YELLOW sticky trap

It is. I do it like this now, guess I was overwatering the last week's..tho it's my fault having those issues.
My DE will arrive on Monday. They will get drenched, that's for sure and the pot as well haha

 

[Eledin]

It is. I do it like this now, guess I was overwatering the last week's..tho it's my fault having those issues.
My DE will arrive on Monday. They will get drenched, that's for sure and the pot as well haha

When you over water them the leaves droop slightly, when theyre thirsty you get the same drooping. If you wanna keep it dry as much as possible for the DE to be effective dont water them til they ask you to, in that period they should all die. DE works 100% of the times but you gotta do it how its suposed to be done, everything covered and mixed with the top soil and dry, extra on the borders so they dont dig in to put eggs and on the bottom if youre using plastic pots because yes, they can still put eggs through the draining holes.

 

[Redneckx]

Baking powder, or soda, will spike your soil pH to high levels.
This will most likely shock your plants and make certain nutrients unavailable to the plants due to pH uptake requirements of each nutrient.
If a powder is to be used, diatomatious earth is the one. It is crushed diatomes, witch are essentially microscopic seashells, which will break the insects epidermis causing them to dry out and die off. It is pH neutral, and offered a natural slow-release of silica.
Neem oil is excellent, but as you mention, should not be used on flowers. Root drench is okay in small doses during flower, but also will be detrimental to beneficial nematodes if you are using them. Diatomacious earth will also negativly impact nematodes.

Thank you for those necessary and detailed informations!
Thought that baking powder can cause in serious issues that's why I avoided it.
I don't use nematodes so it's no biggy.

 

[GGOGZin]

It is. I do it like this now, guess I was overwatering the last week's..tho it's my fault having those issues.
My DE will arrive on Monday. They will get drenched, that's for sure and the pot as well haha

over and under watering is pretty easy to do even when you know what you’re doing. The most important advice you can probably get is to allow your soil to dry out as much as you can before watering again. Common misinterpretation is that over watering means adding too much water at one time but that’s not the case, it’s actually referring to watering too often and not allowing your soil to adequately dry out. Roots need to breathe and they can’t do that well if they’re soaked. Your plants will tell you what’s up by their leaf positions and will let you know when they’re thirsty. I usually wait 3-4 days between waterings and allow a full dry out of my growing media, and drill holes all around my buckets this will help ensure gnats can’t thrive and it’ll force your plants to use the majority of what you give them too

 

[Redneckx]

When you over water them the leaves droop slightly, when theyre thirsty you get the same drooping. If you wanna keep it dry as much as possible for the DE to be effective dont water them til they ask you to, in that period they should all die. DE works 100% of the times but you gotta do it how its suposed to be done, everything covered and mixed with the top soil and dry, extra on the borders so they dont dig in to put eggs and on the bottom if youre using plastic pots because yes, they can still put eggs through the draining holes.

I'm trying to keep the soil dry as possible.
When watering half of the regular amount, there is no drain and that can cause in a nute lock right?
If you say that they lay their eggs everywhere i want to flush those mf until the drainage layer. All need to die...
Mixing the top soil with DE and spread a little at last step. Using air pots, so flushing could be effective

 

[Redneckx]

over and under watering is pretty easy to do even when you know what you’re doing. The most important advice you can probably get is to allow your soil to dry out as much as you can before watering again. Common misinterpretation is that over watering means adding too much water at one time but that’s not the case, it’s actually referring to watering too often and not allowing your soil to adequately dry out. Roots need to breathe and they can’t do that well if they’re soaked. Your plants will tell you what’s up by their leaf positions and will let you know when they’re thirsty. I usually wait 3-4 days between waterings and allow a full dry out of my growing media, and drill holes all around my buckets this will help ensure gnats can’t thrive and it’ll force your plants to use the majority of what you give them too

I prefer giving them as much water as possible right until a little drain comes out, do they need too long to dry out to get some oxygen? How much water do you give your plants?

 

[Eledin]

I'm trying to keep the soil dry as possible.
When watering half of the regular amount, there is no drain and that can cause in a nute lock right?
If you say that they lay their eggs everywhere i want to flush those mf until the drainage layer. All need to die...
Mixing the top soil with DE and spread a little at last step. Using air pots, so flushing could be effective

Flushing is for emergencies only and can damage the plant, dont do it. Fungus gnats lay eggs just a couple of inches deep into the soil, but if there's a crack without diatomaceous earth they can go deeper, but not because they are capable of colonizing deep but because there's an aperture, same with the draining holes. Theyre only laying eggs in a thin layer on top or below in your substrate thats why DE kills them all. Its not about the ammount of water you use either, if you use little water but you still leave the DE wet its not gonna do anything. Try giving them a really good watering, maybe get a 10% of runoff or so and then dont water them until they ask you to, droopy leaves (they will become droopy when you water them good, then go back to normal, then droop again when theyre thirsty, then you water them, should take a few days)
EDIT: They also LOVE wet substrate, if your substrate is constantly wet there's no way youre gonna get rid of them.