How to Get Rid of Fungus Gnats

If you love having indoor plants, chances are you’ve had a few uninvited guests in your house as a consequence. Fungus gnats (sometimes mistaken for fruit flies) are one of the most common and annoying of these unwanted visitors, so we’ve collected a few different methods you can use to try to evict them from your plants and your home.

Fungus gnats are annoying but harmless for humans, but their larvae will eat the roots of your plants. They’re attracted to moist soil, so the first step to avoiding them is to get yourself on a good watering schedule that avoids over watering. Quarantine any new plants and let them dry out completely before bringing them in, if you can. If it’s too late for that, it’s time to get creative.

Fungus Gnat Larvae Control

Let’s deal with gnat larvae first. One method is to let the top layer of your potting soil dry out, and then water with a mix of one part 3% hydrogen peroxide to four parts water. It will fizz, which is normal – and it should kill the gnat larvae. You can repeat this until your gnat problem is solved.

Another method you can use to get rid of gnats is to remove the top two inches of soil and dispose of it. Replace it with sand, which dries out quickly and doesn’t contain the organic matter soil does. This way the gnats won’t lay their eggs in it.

Yet another method is to purchase food grade diatomaceous earth – you can mix it in with your potting soil before planting, or mix it into the top few inches of soil to rid your plant of gnat larvae. You can also try a generous sprinkling of cinnamon, which is a fungicide, over the top of your potting soil.

Mosquito dunks, which are usually used to keep mosquito larvae from places like fountains and fish ponds, are another good solution to a fungus gnat infestation. Soak the dunk in your watering can overnight, pull it out, and water your plants. You can repeat the process until your plants are finally gnat free.

Adult Fungus Gnat Control

Now for the adult gnats.... To catch the adults, pop open a sweet drink. Some people use apple cider vinegar or red wine vinegar (or, heck, even just red wine if you’re willing to share it with gnats). You can pour this into a saucer, or craft a little lid with holes poked in to trap them in the dish once they enter. Place it near the affected plants and prepare to collect your dead gnats. Repeat as necessary.

Sticky/fly paper will also help cut down on the adult gnats, if you can’t leave unattended liquids sitting around the house.

These are only a few of the ways that people get rid of fungus gnats, but as always you can check in with the members of the HPH Facebook group for individualized advice!