Get Rid of Fungus Gnats Quickly Without Getting Rid Your Houseplants!

This post is inspired by one of my friends who tried growing plants and got rid of them because of fungus gnats.

He didn’t realize that fungus gnats could be controlled quickly and effectively, and he couldn’t take them flying around his face anymore.

So, he got rid of the healthy houseplants he had cared for successfully for many months as a first-time houseplant parent. It was so disappointing to hear this!

I do get it, though. If you’ve ever had a large fungus gnat infestation, you’ll know that it can be incredibly annoying, tiring, and downright disgusting to be swatting them out of your face, away from your food, and out of your screens when you are just trying to live your life.

However, there is hope! You can manage these nuisance pests and keep your plants!

Today we will discuss my best tips for eliminating the dreaded fungus gnat!

Table of Contents

Tip #1: Fungus gnats need moisture to grow into adults and reproduce. No more moisture = No more babies.

Fungus gnats grow from egg through the adult stage in the top inch of moist potting mix.

In this layer, they feed on fungus and organic matter until they reach adulthood, when they are then able to fly (and annoy us).

They need moisture in this top layer of potting mix in order to survive and thrive until adulthood.

This means that well-watered plants and plants that sit too wet are great breeding grounds for gnats.

Adults also need moist potting mix to lay eggs into. If the potting mix is dry or inaccessible due to a layer of rocks or sand, they will not be able to deposit the eggs.

One way to combat these pests is to allow your plants to dry out at the top. It’s that simple.

Many of our houseplants prefer to dry out partially anyway, so most will handle this quite well.

If you have ferns, carnivorous plants, or other plants that are more sensitive to drying out, this can be a bit trickier, however. So keep reading!

Will the fungus gnat larvae hurt your plants?

Most likely, no. It would have to be a severe infestation where the larvae run out of organic matter to survive on and turn to eating plant roots before they do any harm to the plants. In a home, this is very unlikely.

Fungus Gnats Soil
Fungus Gnats in the Soil

Tip#2 To control the pesky flying adults, control the younger generations easily and inexpensively.

Even though the adult generation typically causes us the most distress, the larvae are the biggest problem because they are multiplying rapidly and hidden within our plant’s soil.

Hundreds of eggs are laid each time a female breeds, and each time fungus gnats reach adulthood, there are more females to potentially lay.

This leads to exponential growth over just a few short weeks. That’s why a few gnats can quickly turn into a huge infestation.

For those of us with many houseplants or houseplants that cannot withstand drying out, trying to control the egg and larval stages can feel daunting. But it is doable!

The easiest and most affordable method (beyond letting the pot dry out at the top) is to use mosquito bits or mosquito dunks.

Mosquito bits are created to help people control mosquitos and fungus gnats naturally

I will insert a snippet from Arbico Organics describing Mosquito Bits below in much greater detail than I can:

“Mosquito Bits are little pieces of a highly effective biopesticide that works in standing water to kill mosquito larvae and in soil or growing media to kill fungus gnat larvae.

When applied to water, it will release Bacillus thuringiensis sp israelensis (Bti), a naturally occurring bacterium that acts as a species-specific larvicide.

As it dissipates in the water, the larvae that’s present will feed on it and perish within 24 hours. After application Mosquito Bits will provide control that will last up to 14 days in water with low to moderate organic content.”

Arbico Organics, Mosquito Bits product page, Source Link

Mosquito Bits are typically available locally at stores in the United States, can be purchased from beneficial bug retailers (like Arbico Organics), and are also available on Amazon.

Here’s a link to Amazon for the Mosquito Bits that I use.*

*This link is provided through the affiliate program, which means that if you purchase the product using my link I may make a small amount at no cost to you. Anything I do make goes back to directly support this blog and my work with plants. Thank you very much for your support!

Mosquito Bits
Mosquito Bits
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Tip #3 To reduce the current generation of flying adults, use sticky traps.

Sticky traps are designed to help reduce the number of currently flying adult fungus gnats.

Adult fungus gnats are attracted to the color yellow. The sticky trap features this bright color and is coated in sticky goo so when the fungus gnat lands on it, it gets stuck and can no longer annoy you or procreate.

The traps are very inexpensive and are typically available as either stakes to push directly into plant pots or hangers to hang near plants.

Because fungus gnats like to be right at the soil’s surface, I lean toward the stake variety. Both can work, however.

The only real downside with these is that they are pretty ugly, in my opinion. But they are effective. So it’s a situation where you have to decide what is worse: annoying fungus gnats or ugly yellow sticky traps. 🙂

Yellow Sticky Traps on Amazon*

*This link is provided through the affiliate program, which means that if you purchase the product using my link I may make a small amount at no cost to you. Anything I do make goes back to directly support this blog and my work with plants. Thank you very much for your support!

Sticky Traps
Sticky Traps

Tip #4 Know that fungus gnats commonly reoccur and prepare for it because they can find ways back in a house, even with perfect houseplant care.

Fungus gnats can fly in through windows, come in with new houseplants, and the eggs are often present in bags of houseplant potting mix.

The fungus gnat eggs can stay dormant, waiting for the right conditions to begin to grow and develop.

Because of fungus gnat eggs and other concerns, some people will sterilize new soil with boiling water or by baking it. I’m not necessarily recommending this as I’ve never done it or felt the need to.

However, know that fungus gnats are likely to hitch a ride into your house again through these means, so you can be prepared for when/if they do arise.

If you have mosquito bits and/or sticky traps on hand, you can immediately put these measures in place and stop fungus gnats from ever becoming a true nuisance.

Marantaleuconeura
Maranta leuconeura

Bonus Tip: Try Beneficial Nematodes for fungus gnat control if you have a lot of plants.

Beneficial Nematodes is another great fungus gnat control option. They are a naturally occurring microorganism that lives in the soil.

You can purchase them as a powder, which can be added to water and then watered into your houseplants.

Once watered into a houseplant, these beneficial organisms use the larval stage of fungus gnats (as well as thrips and other nasty pests) to reproduce. They parasitize the larva.

This allows the beneficial nematodes to live on and naturally controls the fungus gnat populations.

Beneficial nematodes are commonly available from online retailers who sell other beneficial bugs, like Arbico Organics or Nature’s Good Guys.

I highly recommend trying this method if you have a lot of plants and are willing to invest a few extra dollars to help them remain healthy and you retain sanity.

Especially if you are also battling thrips, beneficial nematodes are a real game-changer, particularly in large plant collections.

Summary

Fungus gnats are annoying but mostly harmless pests that spend their juvenile lives in the top inch of potting mix.

Letting the top inch of potting mix thoroughly dry and/or adding mosquito bits will control fungus gnats before they make it to adulthood.

However, adding sticky traps can also reduce the number of current flying adults.

The frustrating fungus gnat can be managed through these steps so that caring for houseplants can be enjoyable and gnat-free (most of the time, anyway).

Happy Growing! See you next week!

Disclaimer

This advice may not work for every houseplant grower, but it works for me and my plants!

If you do something different that works better for you, share it in the comments below! That’s how we learn and grow as a community. 🙂

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