How to Combat Fungus Gnats on Houseplants

Fungus gnats: the bane of every houseplant collector. They dive bomb your cup of tea mid-sip. They swarm your fruit. And worst of all, they use your precious houseplants as a breeding ground. One single female fungus gnat can lay up to 300 eggs a week. Now, imagine you already have 15 in your house. Yikes!

What Are Fungus Gnats?

Ever seen those tiny, black gnats flying around your plants? Or maybe you brought home a new plant and, when you gave it a little shake, a swarm of flying bugs emerged. Chances are, those are fungus gnats. These pests aren’t just annoying—they can damage your plants, too. The larvae feed on your plant roots, weakening them over time. They’re not just a nuisance; they’re a potential threat to the health of your greenery.

So, now that we know how gross and problematic fungus gnats can be, what do we do about them? Don’t worry, I’ve got you covered with 7 proven ways to prevent and combat these pesky critters.

1. Avoid Overwatering

This is hands down the most important step in preventing fungus gnats. These pests are attracted to moist soil, where they lay their eggs. While it's tempting to water your plants on a strict schedule, this isn’t always the best approach.

I recommend checking the soil before watering: poke your finger into the dirt and see if it feels moist. If it doesn’t, then it’s time to water. If you don’t want dirty fingers, you can use a small stick or plant moisture meter (no judgment here if you enjoy the tactile experience, though!).

Overwatering not only encourages fungus gnats but can also cause root rot, which is harmful to your plants. So, by waiting until the soil feels dry, you'll protect your plants and sanity.

2. Sticky Traps

Sticky traps are my go-to tool when I spot fungus gnats in my home. These traps help capture gnats flying out of the soil, as well as any others that might be trying to lay eggs.

I like to place them near my plants, especially in areas where I notice the most gnat activity. They’re an easy and effective way to reduce the gnat population.

I use this one. They work like a charm!

3. Vinegar Trap

A simple vinegar trap can do wonders if you have a gnat issue. I place a small dish or jar with apple cider vinegar in areas where I see the most gnats.

The sweet smell attracts them, and the soap I add helps trap them. I’ve had great success with this method!

Some people recommend covering the jar with plastic wrap and poking small holes in it, which traps gnats more effectively. Personally, I find just leaving the jar uncovered works perfectly fine.

4. Cinnamon

Cinnamon is one of my favorite natural plant remedies. It’s an antifungal and helps keep fungus gnats and mildew at bay.

After repotting plants, I sprinkle a little cinnamon on top of the soil, especially those I don’t want to treat with chemical insecticides (like my banana trees or avocado plants I bring indoor each winter).

This also helps prevent mildew that sometimes forms when plants transition from outdoors to indoors.

Pro tip: If you're repotting a plant and don't want any bugs hitching a ride, a light cinnamon sprinkle is a great, eco-friendly option.

5. Systemic Granules

I use systemic granules for any houseplants I don’t plan to consume the fruits of. These insecticides work wonders because they’re absorbed into the plant’s roots, repelling the pests that feed on them.

I’ve been into houseplants for over five years, and while I’ve had a few outbreaks of fungus gnats, I’ve never had an issue with other pests like mealybugs or aphids—thanks to the systemic granules.

I use this brand and highly recommend it. It’s given me peace of mind knowing that my plants are protected.

Note: Consistency is key, as systemic granules work best when applied regularly. If I skip a few months, that's when the gnats make an appearance.

Conclusion: Fungus Gnats Don’t Stand a Chance

Fungus gnats may be a persistent nuisance, but with these five simple steps, you can rid your home of these pesky critters and keep your houseplants thriving.

Remember: the most effective way to tackle the problem is a combination of prevention (like avoiding overwatering) and active treatment (like using sticky traps and vinegar).

Follow these tips, and you’ll have a gnat-free home and happy, healthy plants in no time!

Additional Tip: To prevent gnats from hitching a ride into your home, consider checking plants for pests before bringing them inside. It’s always better to catch an issue early.

What do you do to combat fungus gnats? Share your tips in the comments below