A New Weapon in the War Against Fungus Gnats

bag of gnat nix

Last Week I received a great new product to test for fungus gnat control. It’s not an insecticide or a pesticide; rather it’s a barrier method for keeping the adult gnats for burrowing down into the soil of the plants and laying eggs.

Those of you that have followed me for awhile will remember that I have a huge problem with fungus gnats. The problem starts every fall–I’m already seeing traces of them but the problem isn’t out of control yet–and if it gets really bad it can persist into March or so.

I’ve posted about the problem last year and I spent most of February 2012 on a rant posting about in and all the different things I was doing to try to combat the problem since I had so very unwisely used some moisture control soil that I had left over from a client. By was that a learning experience! Never again!

This product, as you can see, is called Gnat-nix and it is made from recycled glass (which you wouldn’t really know unless you read the product literature or the bag). You put a 1/2″ to 3/4″ layer of the product on the surface of the affected plants and the pesky gnats aren’t able to burrow their way down into the soil to lay their eggs.

As I have previously explained in various posts (which start about here, by the way,http://wp.me/pOm4T-1ws), as annoying as the gnats are, it is the larva that do the damage to the plants. And of course, the larva grow up to be more gnats, causing a vicious cycle of gnats, eggs, larva and more gnats. By mid-winter, the gnats are dive bombing your food and drink. It’s just delightful.

So I have high hopes for this product and getting ahead of the fungus gnat problem this year. I’ll keep you posted!

4 thoughts on “A New Weapon in the War Against Fungus Gnats

  1. Nancy Turner June 15, 2015 / 10:15 am


    I was wondering if you had had any success with controlling fungus gnats in your plants using GnatNix. I recently discovered that my weeping fig tree and a smaller bonsai plant were infested with gnats, and although the I’ve applied a thick layer of the material, I see that the gnats are walking over the material still (4 days later).

    Thank you.

    • gardendaze June 15, 2015 / 11:11 am

      Hi Nancy,
      I didn’t have the occasion to try it. My fungus gnat population this winter was practically non-existent for the first time in 3 years. I feel blessed–but at the same time, I feel bad about not testing the product.

      If you only have a problem with 2 plants, you have a couple of options. If they’re manageable, you can either put them outside, where nature will quickly take care of that little problem for you.

      If that’s not an option, or one you’d prefer not to take, you can re-pot them. Take care, if at all possible (and it’s nearly impossible these days!) to get a soil without the “wetting” agents in it. At all costs avoid the “moisture control” type soils. They never permit you to let the soil dry properly and therefore, the fungus gnats always have a home around the roots.

      If you’re still seeing adults gnats around the top of the stones, I wouldn’t worry too much. They’re probably looking for a way down to the soil to lay their eggs. The adults are not really the problem, of course (other than the fact that they are annoying as heck to us!) It’s their larva that eat the roots of the plants–the things we can’t really see that’s going on down in the soil.

      The fungus gnat cycle is 28 days from egg to adult so it may take awhile for this entire “cycle” to complete and all the living gnats to die. But if the living gnats can’t get to the soil the breed, that’s the goal, and that’s the point of the gnatnix–so try to be patient–or try one of my other suggestions, above.

      Fungus gnats are one of the most persistent and troublesome little house plant pests!

      Good luck!


      • Delia Paul July 3, 2015 / 3:36 pm

        I’ve always had success (eventually) covering the soil with sand (as Karla recommended to me). Sand has the good or bad feature of slowly disappearing into the soil. What’s this gnat mix look like? Is it better looking than sand, or larger granules?

      • gardendaze July 3, 2015 / 5:25 pm

        It’s made of recycled glass although you can’t really tell that by looking. If you’re familiar with the sorts of mixes that they top cactus arrangements with –not the smallest beige pebbles but more like the larger terra cotta colored pieces–it somewhat resembles those. Needless to say, it won’t break down or be absorbed into the soil all that easily.


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