Do Fungus Gnats Really Effect plants that Much

Any input or comments of this??

Yes I seen the affects of them on my plants the one that got infested started having difficency problems. They also die on your buds and can cause mold and stuff. I have been picking them off as I see them. The buds on the one that was affected seem smaller but maybe just a different phenotype not sure. This has been my experience with them. They ate my gfs spider plant roots up. I pulled the plant out of the pot got rid of the dirt and am now saving her plants in the whole house with my nutrients from growing.

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I had them pretty bad my last grow. Might be part of the issues I had.

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The adult (flying) stage of the fungus gnat is not much more than an annoyance.

It is the larval stage in the soil that does the damage - eating your plants roots.

Most often they appear as one of the consequences of over watering.


She has an ivy plant that I used vinagar soap and water and killed so many damn bugs. Unreal now her plants are taking off she wont even touch them anymore lol.

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A peroxide drench works too. They are part of the reason I’m doing coco.


I moved her spider plant into coco now its finally stating to recover after 3 weeks. Doesnt get much light just being in the house so I get the delay especially seeing as how there was no roots left. They make a plant show alot.of dificencys by eating and dmging the roots.

They can kill your plants, thats pretty bad, i always have the below product at hand.

Bti Bacillus thuringiensis israelensis

you need to get the above product, you can get it on ebay mix a strong solution then PH the water to your requirements it will kill the larvae worms which eat the roots of your plants, you need to do it every watering until your ontop of them, i dont have any probs now but still use it at least once a month just in case.

Kill Fungus Gnats with 1 oz GNATROL BTI bacillus thuringiensis israelensis

Brand new

From United States

Seller: organicbti (4,768) 99.7%

Buy It Now

Item: 264084569719

sorry not allowed to put the ebay link on but the sellers details are above and they are in the USA
also if you have any other indoor plants treat them also.
Compliment this with yellow sticky boards and topdress with gnatnix which is a recycled glass.


Bought this just to have on hand. Just in case…

I’ve used this

It seems reduce their numbers, but never knocked them
down completely.

you have to get the above but in the pure powder form that you mix with water, then PH it and it will get to the roots when you water thoroughly where the Gnat larvae live and eat your roots, then you have to keep reapplying for the whole life cycle hence the yellow sticky boards and the Gnatnix that you put as a complete top dress on your soil, the yellow cards also help you see how many gnats are still around, it has worked for me, that means it can work for others! It may be expensive but not as expensive as losing a plant or two, or significantly losing yields.

I feel fungus gnats, along with aphids and mites, really impacted my LA confidential grow significantly. I had a lot of leaf dropping.

I still have them, but I do the peroxide thing and it’s kept them at bay

I would not use Hydrogen peroxide on a regular basis as it can be detrimental to root growth and also kills other soil life.

As an environmental friendly alternative compared to other insecticides Bti Bacillus thuringiensis israelensis is used multiple times per year in the Upper Rhine Valley in nature conservation areas of European value.

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Check out a product called Gnat Nix . I use a 1/2 inch layer on top of the soil and sticky fly tape . One week gnats are gone . No chemicals is the part I like about it .


Scroll up to my earlier post, great minds think alike :+1:

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Ahhh good job @Hungrybud , I missed that one .lol. Need sleep !

If you put a top dressing on you can divert them to that while you control/rid of them.

They will eat dead plant matter/dressing before your roots.

Gnat Nix works folks! I’ve used it with great success. Mosquito bits also have BTi and is another good option. I’ve tried a lot of other ways to control them without much success until I tried the Gnat Nix :v::bear:


This is also sold as Mosquito Bits or Mosquito Dunks. Available on amazon or local hardware stores or nurseries.

EDIT: you could also use spinosad (available as “Captain Jack’s Deadbug”) - another all natural, predator based solution.

Check my no-till thread if they’re still an issue. Lots of organic pest solution ideas there as well.

Yes know the products well, Spinosad well actually the first strain Saccharopolyspora spinosa was found in a old caribbean rum still in 1982. It works out cheaper in the long run to purchase the pure form of BTI if possible as the Bits and Dunks only have around 10% BTI in them the rest of the product being an inert material, so you pay a lot for the packaging and the name of the products.

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