How To Get Rid Of Gnats In Plants Using Natural Remedies (& Which Ones To Skip)

Being a plant parent is one of life's greatest joys. They're not picky eaters, they don't need help with homework, and they rarely complain. However, you probably don't also want to be the proud parent of hundreds of fungus gnats that your plants might be hosting — and if you've never been on the receiving end of a fungus gnat infestation, consider yourself lucky. The experience is similar to having fruit flies, but actually goes deeper. With fungus gnats, the ones you can see are not your biggest problem; it's the larvae that are lurking below the plant's soil. That's where they do their damage by nibbling away at the plant's roots until the plant is stunted, wilted, or even dead.

Assuming you don't want this problem in your home, the easiest way to stop a fungus gnat infestation is preventing it happening in the first place. The gnats are attracted to plants because of the soil's moisture. Once they've identified an acceptably wet surface, they lay their eggs on top. So if you don't overwater your plants, and thus avoid saturating the top layer of soil, you can avoid the gnats. You can do this by submerging your plant pots in a container of water for up to an hour. 

If you already see the pesky gnats swirling, however, it's time to get down and dirty with some DIY pest control. We're here to tell you which of the most widely suggested treatments against fungus gnats are the easiest, safest, and most effective — and which ones aren't worth your time.

Decades of struggles with fungus gnat infestations have led to many solutions to the problem. One popular method, also used against fruit flies, is to put equal parts of vinegar and water with a few drops of soap in a small bowl. Simply place it near your plant. This will capture some of the flying gnats, but it will do nothing to address the larvae under the soil. So, ultimately, you've not really solved the problem at all. Let's look at other solutions.

Another common remedy is cinnamon and chamomile tea – both are natural fungicides that target the fungus the gnats are feeding on — but there's no scientific evidence for this, so we'll skip any further details. Another approach is to thoroughly drench your plant with hydrogen peroxide diluted with water. This is effective against fungus and bacteria and can kill the gnat larvae. However, this soaking can attract more gnats to the moisture as well as kill all the good microorganisms in the soil, so proceed with caution.

That's basically 0-3 for remedies so far, but never fear, we're about to turn our fortunes around. A very simple and surprisingly effective remedy is using potato. Simply add some small chunks of peeled potato to your plants, just under the soil. The gnat larvae are attracted to the potatoes and will cling to them. For this method to work, you'll need to dispose of and replace the potato pieces every few days as they become coated with larvae. As effective as this is, though, it's still unlikely to completely solve the gnat problem by itself, so let's dial up our approach.

If the aforementioned remedies didn't get rid of the gross bugs in your plants, it's time to reach outside the boundaries of your normal pantry staples. One startlingly effective way to eliminate a fungus gnat infestation is by using nematodes, microscopic worms that feed on bacteria, fungi, and insect larvae. You can buy bagfuls of these little creatures online. A small bag of 5 million nematodes from BioLogic is more than enough to treat many, many plants.

To make sure that the gnats never return, try a method called top dressing. This is where you add a protective layer to your plant soil to discourage the gnats from laying eggs there again. The layer should be at least a half inch thick and can be sand, fine gravel, or you can go with a 10 lb. bag of HARRIS diatomaceous earth, which comes in powdered form. This method is most effective once you've cured the initial infestation. No more uninvited guests in your home nursery!

And if you're uncomfortable with unleashing a tiny (yet harmless) army of worms into your plants or sprinkling diatomaceous earth, well... at that point, you're left with yellow sticky traps. They aren't a truly natural remedy, but they're still better than spraying chemicals, and gnats genuinely are attracted to the bright color. Otherwise, though, the nematodes, potatoes, and-or top dressing are going to be your best anti-gnat bets.