Hey folks, just want to reiterate that a layer of perlite on top of your soil will break most infestations. I switched to 70/30 coco perlite mix and I haven’t seen a bug in a long time.
I know it sounds too simple but I tried every single thing recommended over the years, NOTHING actually worked but the perlite.
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I have heard that as well. I get them here and there. Never enough to be a problem. For me it’s all based on my spray game. Sometimes I get lazy and it bites me in the ass. We have a soil here in Michigan called Potters Gold and it’s good and bug free. It’s made locally and I would recommended it to any soil grower. Some brands are notorious for it or at least they were. I made the switch and never looked back.
I’ve often wondered if fungus gnats can live in a little ecosystem inside a plastic bag filled with potting mix. Or any bugs for that matter.
Sorry if somebody has already mentioned this (Looong thread and I’ve only just started going through the whole thing!) Besides the yellow being the most attractive color for FG, the ‘shape’ is also very important! Studies have proven that ‘round’ shapes attract more FG. Coat a lemon (on a stick) with a thin layer of Tanglefoot and place the stick in your growbag an inch or two off the soil. Come back to find you now have hairy brown balls! 
Even works for women growers!
Also, be very careful NOT to use DE along with Neem or other oil-based products - they interact in a way that causes leaf burn. I’ve been using DE to get rid of mites after a truckload of mites were delivered with my rice hulls. I caught it before they even managed to get onto the plants (much) and have been sprinkling DE on the soil surface and scruffing it up to a 1/2" depth. Seems to have made a big impact so far…we’ll see about long-term. Okay, back to catching up on this thread! Thanks for the ideas all!
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This stuff works great, 1/8cup per gallon of water spray down the top and sides of your pot thoroughly, and let loose on the rest of the grow area/canopy if your in veg/early flower idk about late flower but I wouldn’t risk it.
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I noticed some fungus gnats in the grow room.
I live on a small island and cannot get the recommended preparations. By the time it arrives in the mail…
Do you think it would be good to cover the soil with Non-Woven Geotextile?
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Yes but making sure they can’t get in underneath or you can bottom feed so top stays dry and if in regular pots use fabric to block bottom holes too
: )
They are best methods to use, no need for anything else if you do this , easy fix
@Pannonian
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I use regular pots. I will do as you say.
Thank you @ifish
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When I had fungus gnats I let the top inch of soil dry out. Then I used a shop vac to remove the top layer of soil and replaced it with play sand. I was using regular house plant pots. After that grow I switched to fabric pots which dries the soil out faster than plastic and water from the bottom and no more fungus gnats.
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I can’t say that it was miraculous to eradicate them, but “womans pantyhose” is pretty convenient and cheap for low volumes.
It avoid the migration from one plant to another and permit to quickly spray the whole root mass on all the perimeter with your weapons.
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This stuff works well. Capful per 5 gallons. Use a tray to bottom feed and fill tray to the top of drainage holes and water the top as well. A buddy turned me on to it recently and it worked great. Use with every watering. Results are noticeable in a week and after month of doing this I rarely see any.
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THIS. I don’t know why people refuse the easy and foolproof solution and want to play with lotions and potions.
Wrong. Predator mites are 100% effective.
Microbe Lift BMC, hypoaspis, and nematodes are all great. Fungus gnats are the easiest bug to deal with.
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Water less 
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Get a 5,000,000,000 pack. Apply as they say. Total destruction of them.
EDIT: you can also place pots in deeper saucers, filling them up, over top down watering. Once the top layer dries out, the gnats vacate.
Dry sheets, will reduce them.
Layer of sand, will reduce them.
The Biologicals will eradicate them
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I use Fox Farm Ocean Forest and as such am pretty much guaranteed to have fungus gnats. I don’t wait to see them to treat for them. As soon as I put the soil in a plastic pot or fabric pot I sprinkle Mosquito Bits around on the surface and water them in lightly. I also buy the stick paper in sheets and cut 1.5" wide strips that I staple around the inside of the rim right at soil level.
As with any pests a preemptive strike is the key to success. Treat before you have a problem cause having pests takes most of the pleasure out of growing.
Also, fungus gnats are easier to control if growing in fabric pots because there are no holes at the bottom for them to enter and access the root system. And fans blowing across the top of your soil is a great deterrent. If they can’t land because they’re getting blown away from the plants they can’t propagate.
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Microbe Lift BMC and glycerin or potassium salt soap drenches
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Yes this makes a huge difference for me! My fabric pots are quite tall at 18” plus 2” of saucer and plastic elevator, so a $25 Walmart oscillating 12” desk fan on a milk crate is perfectly 2/3 below the top edge. I leave it on 24/7 on speed two oscillating across the soil surface and I think it makes a huge difference with the gnats!
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The last bag of roots organics I got seemed to have a little Fungus gnats here and there outside the bag when I got it home and I’ve forsure seen some more in the grow since I’ve used a bit of it. but as the rest of this tub of soil sat on some hotter days and then I opened it, there’s a good bit of fungus gnats flyin around and The tub was more humid than usual is there anything you guys mix in the soil for storing it and maybe keeping a little dryer on some more warm humid times? Maybe some more perlite or dry coco chunks to help with that? Or would the soil be ok if it wasn’t for the fungus gnats in it that since I bought it. It’s inside not super hot or super humid , I’m just gonna use the rest of this bag of soil outside because it seems when I began to use this a lot more fungus gnats were around the grow. I’m gonna water the plants with some mammoth canncontrol and let the ladybugs and other bugs I got take care of the big ones. Gonna get some fresh soil from another shop cuz that was the first bag that I’ve seen em in right when I get home like that
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