5 Reasons Why Your Indoor Plants Are Attracting Fungus Gnats

Let’s be honest—fungus gnats are one of the most annoying things about owning houseplants. You’re watering your plants, admiring your lovely indoor jungle, and then suddenly, tiny black flies are buzzing around your face. They’re harmless to you, but they can damage your plants if left unchecked. Over the years, I’ve had my fair share of battles with these pesky critters, and I’ve learned that fungus gnats are usually a symptom of something off in your plant care routine.

If you’ve got fungus gnats, don’t worry—most of us have been there! Here are five common reasons why they’re showing up, along with some simple tips to deal with them.

1. You Might Be Overwatering

I get it—watering your plants can feel like you’re nurturing them. But fungus gnats love damp soil, and overwatering creates the perfect breeding ground for them. They lay their eggs in moist soil, and before you know it, there’s a full-blown infestation.

What I Do Instead:
Let the soil dry out between waterings. Most houseplants are fine with their topsoil completely drying out before you water again. I always check by sticking my finger in the soil—if it feels dry an inch or two down, it’s time to water. A moisture meter can also be handy if you’re unsure.

2. Your Pot Might Have Poor Drainage

Even if you’re not overwatering, a pot without proper drainage can trap water in the soil. Soggy soil equals happy fungus gnats.

My Fix:
I make sure all my pots have drainage holes (and if they don’t, I drill them). For decorative pots, I’ll keep the plant in a nursery pot and place it inside the pretty one. That way, any extra water can easily be dumped out. I also sometimes add a layer of gravel or mesh at the bottom to improve drainage.

3. Your Soil Could Be Too Rich

Fungus gnats thrive in soil that’s packed with organic matter like compost or peat moss because it gives their larvae plenty to eat. While that’s great for plants, it can be a magnet for gnats.

Here’s What I Do:
I’ve started using peat-free soil mixes that are well-draining but don’t have too much organic material. You can also top the soil with a thin layer of sand or gravel—this makes it harder for gnats to reach the soil to lay their eggs.

4. You Brought Them in from Outside

If you move your plants outside during summer (or buy new ones from the garden centre), gnats might hitch a ride indoors. I’ve made this mistake before—it’s such an easy way for pests to sneak in.

What I Do Now:
Whenever I bring plants inside, I give them a good once-over. I check the leaves and soil for any signs of pests. If I see anything suspicious, I’ll repot the plant in fresh soil and quarantine it for a few days just to be safe.

5. You’ve Let an Infestation Get Ahead of You

If you’ve already got a few gnats flying around, don’t ignore them. They reproduce fast, and the larvae can damage your plants by munching on the roots.

How I Tackle It:
I swear by yellow sticky traps to catch the adult gnats—they’re oddly satisfying to use. For the larvae, I water the plant with a diluted hydrogen peroxide mix (1 part hydrogen peroxide to 4 parts water). Neem oil works well, too, and it keeps gnats from coming back.

A Few Extra Tips

To keep fungus gnats at bay, it’s all about prevention. I always make sure to remove fallen leaves and debris from the soil, avoid letting water sit in saucers, and keep an eye on my plants for any signs of pests.

Fungus gnats are annoying, but they’re not the end of the world. With a few simple changes to your plant care routine, you can say goodbye to those pesky flies and keep your plants happy and healthy.

If you’re dealing with other plant problems or just want more tips, check out the rest of our blog here.