Help! Fungus gnats

I need help please! I’m a true beginner I’ve only ever bought plants that were fully grown. I’ve never started from a seed before. So I have lots of questions. My main concern is fungus gnats. I know they fully stunted the growth to at least 2 of my plants. I’ve replaced the top inch of soil and I’m going to start bottom feeding. But even after removing the infested soil I still noticed some gnats this morning. What can I do??

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In, so I can see response

So first, dry your soil out more between waterings. Pick your pots up when they are completely dry to see their weight.

Neem oil–water it into the soil or add it as small pellets. Spray foliar

Yellow sticky traps—they work, get the big ones.

DE(Diatomaceous earth) as a top dressing on soil.

Add a quick drying top layer e.g. perlite, sand etc 2 inches deep.

Fans blowing at soil level

If you have a true infestation I’d would reccomend a hydrogen peroxide flooding of your soil. Followed by the above steps.

But if you dont dry your soil out they WILL come back


Mosquito bits soaked in water strain out the bits and use the water as you normally would. One cap full per gallon soaked overnight. This will need to be repeated a couple times as eggs hatch the bits only kills the larvae, yellow sticky traps will take out the adults


I planted this one 2/20 it had the worst infestation

It got to this point about 2 weeks ago and hasn’t grown since. I’m hoping it will recover :crossed_fingers:t3:

You might be able transplant it see if that helps that’s what I would do

@Barron I personally use nematodes to kill and prevent gnats. Spray soil with nematodes and they will kill the larvae and use sticky traps to catch the adults.

Another method that works for me is using garlic spray as a deterrent and using DE on the soil.

I usually keep gnats under control with these but if they get way out of hand and I can’t get them under control I will do a neem drench, garlic drench, bti, or a hydrogen peroxide drench.


Thank you rye! I’m ordering the traps now. I took off the first inch of soil and put fresh soil and dryer it out. I’m going to try bottom feeding so the tops won’t be wet :crossed_fingers:t3::crossed_fingers:t3:


If these suckers come back I’ll be trying these methods too!


If you don’t treat the durt they will keep coming back it only takes one to lay eggs


Since they seem to be gone I’m going to get some DE and go that route


do not forget, that nano micelle solution I sent you will help with gnat control. Use it 2x strength…1 bottle for a gallon (mold prevention, curing, residue rinse, pre drying to prevent mold) and insect control at 1 bottle for 1/2 gal water…drench with mister or even water with it
We should ALL be using DE where possible as gnats come in MOST organic / living soils…
I started my veg garden grows in domes…2 days after adding tomato slices, mold spores…1 spray and I have NOT seen the reemergence of mold at all. I am even going to test this on hydro as usually I get algae on the top of seed starters but everywhere I sprayed, no green algae…
Please let me know when you use it and documentation for my records…


What brand of DE do y’all use?

I had the same problem. Let the little stinkers get out of control and they exploded. First thing I tried was dimatatious earth. Think I kind of messed that up as I put a cup per plant. Once I watered it just gummed up I saw no positive results from this. Second thing I tried was the nematodes. There success is hard to judge becuse they work on a time delay you just dont get instant results. Third thing I tried was the yellow stickey traps. I cought so many gnats I was having to swap traps every couple days as you could not see the yellow any more. But more kept on hatching. Last thing I tried was @Mrb53004 nano solution. I saw instant results with it within hours of spraying gnats were highly agitated and within a week they were gone. I wish I had some way to prove what percentage of the results were dependent on the nematodes and how much was Mikes nano solution. I really dont think the DE and sticky traps were big contributors as i messed up the DE and the traps are more of a gauge than a solution.


PS I had got Mikes nano solution for treating mold (wich it did a wonderful job at) not gnats so I had no control beds set up for the gnat treatments. On the control beds for mold his nano solution is awsome way better residual control than any of the other things I tried. With none of the dried residue on the leaves like other products.

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@Barron I use Harris or Safer brand. Both are OMRI listed.

it washes THC 100% …no residue, organic…I spray at dry time to prevent mold in the drying tent and on/in the buds. If mold is already tunneling through the flower there is NO RECOURSE but preventative is SO MUCH BETTER
Thanks for the POST on the effectiveness of my solution, both MOLD and GNATS…now I just have to figure how to sell it.
I just started my vegetable dome and used it for gnats and mold…both gone in 3 days…
I am still awaiting enough documented results that I can use to go send to the labs for certification…I do not want to make that investment without proof
Then comes patent…geesh, it takes so much $$ to get a product to market…Maybe I could just do it underground, like we have done for years on the grow circle


Explain washes THC? I must be having a old man moment.

washes the plant and leaves the THC CLEAN! no residue, does NOT remove or reduce / impact THC as washing / rinsing with other materials can do. I have tested it in a footbath, soaking buds / stems (soaking, not agitating, scrubbing). Sent the samples (non-washed & washed) to the Lab and there was no difference in THC content or “washed vs unwashed”. Also “ZERO” residue. Great for removing any topical residuals (tea, kelp, molasses, DE, pesticides (not internal…if systemic are used, it would have tunneled through the bud and those are not removable), etc…