Any cheat codes to killing fungus gnats?

keith1975

keith1975

Well-Known Member
I've had so much trouble with Spidermites, I didn't even see the fungus gnat problem coming.

I have:
- sprayed the soil with neem oil
- put diatomaceous earth on the soil
- tried keeping watering to a minimum
- put sticky tape everywhere (and I can see them fill up)

Yet, every day I come back and I see the stupid flies in my soil. And I can also see the plants struggling to grow. Any other suggestions on how to kill them?

Summer growing is off to a bad start. :(
 
h202 flush to kill the larvae. used 29% at 1ml / 1Lt.
no pest strip to decimate any fliers or movers.

no pest strip should only be used if grow areas are separated from living area, or if human exposure can be limited.

i cleared mine in about 10 days.
 
since in soil ... pour 2 - 3 times container size thru
feed within 12 - 24 hrs. some do a 1/4 strength feed immediately after

the h2o2 breaks down pretty quick in to oxy and water.

gnats can be an indicator of unhealthy roots as well. a flush and an up pot as well can be a good thing depending on circumstances.


keep a fan on the soil low down on the plants. gnats are crappy fliers and this makes it difficult for them to land or lay eggs.
 
pine bark mulch in a 1" layer on the top of your soil. It is so effective that it may as well be a cheat code. Turns out the dumb little flying things don't know what to do about an aromatic mulch and they can't figure out how to burrow through it to lay their eggs. Boom, lifecycle is broken.
 
I do not think that the Neem oil will have much effect on the Fungus Gnats.

I tried the Diatomaceous Earth but it was more of a pain than a help.

I held off on the use of Hydrogen Peroxide should work but I did not use it because it can kill off beneficial organisms in the soil.

If you mean the square yellow sticky tag things as sticky tape I noticed that those are more useful for seeing how many get trapped and were useful for telling me how bad the problem was but not for actually helping solve the problem. If you are talking about the sticky ribbons that can be hung from the ceiling then those just catch the ones that are actively flying around which is a very small percentage of the problem. Some of them will give off a poisonous gas for as long as several weeks

That leaves "-tried keeping watering to a minimum" which sounds like you were still giving to much water. The gnats really like moist soil and if you were keeping it to a minimum then I think it is still to much water. What worked for me was to let the soil dry out to the point where the plant is just starting to droop or wilt. If this happened at or just before lights out I would not water until morning or lights on. Without the lights on the plant will not transpire as much and survives just fine until morning while the soil dries out even more. If I noticed the plant wilting in the morning I would wait fust a couple of hours. This works great for plants still in the vegetating stage and those very early in the flowering stage. If already well into flowering then don't let the plant wilt for more than a couple of hours and definitely alllow no severe wilting.

I no longer use peat moss in my soil mix at at ratio higher than 25%. During the height of my gnat problem when I thought that there was some relationship to their population growth spurt and the amount of peat moss in my soil mixes I did some basic experimenting. The more peat moss in the soil mix the more gnats I saw leaving the soil in those specific pots. I still kept peat moss mixed in with the compost in the soil; I just reduced the amount or ratio. I got rid of all the cloning and seed starting soil mixes since those were 50% or more peat moss.

No gnats in about a year.
 
Emilya said:
pine bark mulch in a 1" layer on the top of your soil. It is so effective that it may as well be a cheat code. Turns out the dumb little flying things don't know what to do about an aromatic mulch and they can't figure out how to burrow through it to lay their eggs. Boom, lifecycle is broken.
Click to expand...
Sounds like a winner. If the gnats come back I will have to keep that one in mind.
 
love that pine bark idea @Emilya

i went the napalm route and never looked back lol :cheesygrinsmiley:
 
keith1975 said:
Napalm?
Click to expand...


the no pest strip is likely more drastic. off-gasses a chemical.

death from above stuff.

SmokingWings said:
A joking reference to the drastic step taken to eliminate the gnats once and for all. Pouring a lot of a hydrogen peroxide & water solution into the soil could be considered drastic.:)
Click to expand...


far less so than an emergency 2/3 root chop and up pot which i have also done ... :cheesygrinsmiley:
 
oh yes... :laughtwo:
 
If you're in soil then you can go No-till grow a cover crop and add Rove Beetles.
I water my soil every single day even when I dont have cannabis growing and I got zero fungus gnats.
And you can not water for a year and it wont make any difference.
I've had gnats boil out of a totally closed bag of soil that was sitting under the house for a year.
 

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