4 Tips for Dealing with Fungus Gnats

Fungus gnats are those tiny black or gray flies that love hanging around your plant’s soil. They might look like fruit flies, but they’re actually different—they’re attracted to damp, organic-rich soil instead of your fruit bowl. The adult gnats themselves aren’t super harmful to plants but can certainly be an annoyance to the plant parent.

And since they reproduce pretty quickly, if you see one or two, you’re likely dealing with a whole crew soon. Time to take action!

Fungus gnats don’t hide very well—you’ll usually spot them flying around near the soil’s surface or clinging to your windows. If you notice tiny white or translucent larvae squirming just below the top layer of soil, that’s the next generation waiting to cause trouble.

Here’s a multi-step approach to evicting those gnats from your plant's soil:

• Let the Soil Dry Out: Fungus gnats thrive in moist conditions, so letting the top few inches of soil dry out will help break their life cycle. The larvae need a damp environment to survive, and by cutting off their moisture supply, you’re helping reduce their numbers.
• Sticky Traps: Yellow sticky traps work wonders for catching adult gnats. Place these just above your plant’s soil to trap the flyers before they lay eggs. It won’t stop the larvae, but it’ll help prevent more eggs from being laid.
• Insecticide: Using a plant-safe insecticide (pssst, Arber!) can be a great way to tackle fungus gnats. It’s a quick and effective method to stop the gnats at the source, ensuring your plants stay pest-free without harming their health. Plus, it works on a variety of other plant pests too!
• Hydrogen Peroxide Solution: For a quick fix, mix one part 3% hydrogen peroxide with four parts water, and water your plant’s soil with it. It’ll fizz a little, but that’s a sign it’s working—killing the larvae on contact.
• Beneficial Nematodes: If you want to go the biological route, beneficial nematodes are a tiny, natural predator that loves to feast on fungus gnat larvae. They’re safe for your plants but not so much for those gnat babies!

Now that you’ve got the gnats under control, let’s make sure they don’t come back. Prevention is key:

• Watering Routine: One of the most effective ways to prevent fungus gnats is by not overwatering your plants. Let the top inch or two of soil dry out between waterings, especially during cooler months when plants don’t need as much moisture.
• Good Drainage: Make sure your pots have drainage holes to prevent water from pooling at the bottom. Soggy soil is an open invitation for fungus gnats. Consider using a well-draining soil mix that includes perlite or sand to help keep things airy.