Pest control concerning gnats in soil

trygrowup · Mar 12, 2026

Ohh btw I don't use neem oil on the plant. Only on the soil surface, and not all the time.
I also shield the plant with a cardboard to minimize aerosols hitting the plant.

And last thing.
The Old Match stick trick against gnats.
It turns out that it might still work in some countries.
Thanks to @Week4Bytch checking, it turns out matches can contain of either Sulfur or Antimony Trisulfide. And I heard before they don't like sulfur
So if possible get the sulfur model. The other don't work at all. When i used them until some 20 years ago, 1 match in a 15cm pot worked for at least a month.
I placed it like this

Then i made it wet when i watered. Changed it when it lost the colors. Thats just how i did.
If i had gnats. I placed one match stick and within a week, no more gnats at all. None. Zero.

Zewbacca · Mar 12, 2026

Coconutz said:
I completely eradicated fungus gnats without spending money or using poison.
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A bag over the pot stopped them getting in/out to lay egg and I could squish them with ease.
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A pair of scissors works well at this stage, after watering I'd be cutting them in two.
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My mums, I put each of them in a bag
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Fungus gnats hatched up to 10wk iirc, Google 4wks isn't accurate!!
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Up to 5 gallon iirc?
You can buy these paint bag filters iirc they're 60 micron they keep gnats in/out they're only £1 each if you don't fancy plastic?
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The foundation is there for a good gnat proof screen.
If you sew a draw string top and bottom of the paint filter bag then it would fit any size pot, elastic in the stem drawstring would essentiall

I keep my pots covered it helps prevent fly by egg laying but they're not a guarantee, covering them yeilds other benefits for roots and helps with evaporation/humidity, preventing any interface for salt crystals forming preventing roots from growing in the stratified area.
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That sounds like a bunch of bull but the results are visible

It's all a waste of time if new gnats are getting in, if you're using soil you're almost guaranteed to have gnats thats just the way it is, however if there's no new source you can wipe them out

If you ever see asian beetles in your grow let them live. They are meat eating little sunsabitches.

opt1c · Mar 12, 2026

If I’m ever growing in soil/coco etc indoors I add gnatrol with every watering at diff concentrations depending if gnats are present or not. I always do a lil per gal as a baseline as part of my ipm. Even with freshly brewed compost tea. Only necessary indoors usually.

Joemclain420 · Mar 13, 2026

orggrwr said:
Just want to add that a 3/4 to 1" mulch layer of rice hulls helps a lot. I use them to keep my living soil and top dresses moist with the extra benefit of rarely seeing fungus gnats after the rice hulls go on.

trygrowup said:
I'm gonna wrap it up for my part.
Thank you very much guys.
This has turned out much better than i expected.
I for one have learned some good things here.
Hope others have too.

Personally i'm gonna choose the net method.
I use lids anyway so i'll make some lids of double layer white sheet, but only to cover the top of the pot.
Then if i get runoff i give the bottom tray a few spray of neem oil.
And if it's getting to much i'll take out my vacuum cleaner.
Maybe also the BT thing. First time i hear about that. They don't sell that in grow shops here.

Thanks again for all the input

I put 2 inches of sand on the top of my pots and I have very little gnats. They can’t get through the sand to lay their eggs and I use pool sand

Pest control concerning gnats in soil

Pest control concerning gnats in soil

trygrowup

Zewbacca

opt1c

Joemclain420

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