Gnats in plant soil can be a nuisance for indoor plant parents. These tiny flying insects lay eggs in damp potting mix, and when the eggs hatch, the larvae feed on plant roots and organic matter in the soil. An infestation can quickly get out of hand, damaging your plants. The adult gnats also fly around plants, making them a bothersome pest
If you notice small flies hovering around your houseplants or find larvae crawling in the soil, don’t worry – there are many effective remedies to eliminate gnats in plant soil. With some diligence, you can break their lifecycle and get rid of fungus gnats for good.
What Are Fungus Gnats?
The small flies commonly seen around indoor plants are called fungus gnats. They belong to the Sciaridae family and measure just 2 to 8 mm in length. You’ll recognize them by their dark gray or black mosquito-like appearance and jerky flight pattern. Though adult gnats don’t directly damage plants, their larvae feed on roots and can transmit fungal diseases between plants.
Fungus Gnat Lifecycle
To get rid of gnats in soil effectively it’s important to understand their lifecycle
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Adult females lay up to 300 eggs in potting soil, usually at the base of plants
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After 4-6 days, the eggs hatch into larvae that live in the soil.
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The larvae eat decaying plant matter and fungi in the soil for 2-3 weeks as they grow. They may also chew on plant roots.
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Next, the mature larvae enter the pupal stage, encapsulated in cocoons in the soil for 3-4 days.
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Finally, the adult gnats emerge from the soil to mate and continue the cycle. The adults live for about a week.
Disrupting this lifecycle is key to eliminating fungus gnats for good.
Signs of Fungus Gnats
Watch for these common signs that fungus gnats have infested the soil of your houseplants:
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Tiny flying insects hovering around plants. These could be the adult gnats.
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Larvae crawling on the surface of potting soil. Look for white worms with black heads.
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Poor plant health, yellowing leaves, dead stems – possible signs of larval root damage.
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Adults flying around areas away from plants, like windows, as they emerge from the soil.
If you spot any of these, it’s time to act to get rid of the gnats.
8 Remedies to Eliminate Gnats in Plant Soil
Fortunately, there are many effective natural methods to kill gnats in soil and break their breeding cycle. Here are the top 8 remedies to try:
1. Let Soil Dry Out Between Waterings
Fungus gnats need moist soil to breed. Simply allowing the top few inches of potting mix to dry out before watering again can help eliminate gnats. Dry conditions make it harder for adults to lay eggs and larvae to survive.
2. Use Yellow Sticky Traps
Traps with yellow sticky cards placed just above the soil line can catch adult gnats emerging from the soil. While this won’t kill larvae, it helps control populations.
3. Apply a Hydrogen Peroxide Soil Drench
Mix 1 part 3% hydrogen peroxide with 4 parts water. Water plants thoroughly with this solution to drench the soil and kill gnat eggs and larvae on contact. Repeat every 3-4 days until gnats are gone.
4. Repot Plants in Fresh, Sterile Soil
Heavily infested plants may need to be repotted in new sterile soil to completely eliminate fungus gnats. Discard old potting mix to remove eggs and larvae.
5. Use Neem Oil
Drench soil with a neem oil solution or spray plants to kill larvae and deter adults from laying more eggs. The oil disrupts insect growth and development.
6. Apply Diatomaceous Earth
Sprinkle this non-toxic powdered silica on the soil. The sharp particles kill gnats when they come into contact. Reapply after watering. Wear a mask to avoid inhaling the dust.
7. Use Beneficial Nematodes
These microscopic worms feed on gnat larvae when introduced to soil. Apply as directed on product labels.
8. Set out Apple Cider Vinegar Traps
While less effective than other methods, vinegar traps can help capture some adult gnats.
Be patient, as eliminating fungus gnats takes diligence. Combining several remedies together often works best to fully break their lifecycle. With persistence, you can successfully get rid of these annoying flying pests from your houseplants’ soil and restore their health.
How to Prevent Reinfestation
Once you’ve won the battle against fungus gnats, make sure they don’t return by taking these preventative steps:
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Inspect new plants closely before bringing them home. Quarantine new plants for a few weeks.
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Allow soil to dry out between waterings.
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Avoid overwatering and improve soil drainage.
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Apply an inch of sand or gravel as a top dressing to deter egg-laying adults.
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Use sticky traps continuously to monitor for adults.
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Eliminate excess moisture and fix any leaks that can lead to damp soil.
With vigilance, you can keep these frustrating little pests from wreaking havoc on your indoor plants again. Share your fungus gnat remedies and tips in the comments!
Will Fungus Gnats Hurt My Plants?
Aside from being unbearably annoying, adult fungus gnats wont directly harm your plants. I say “directly” because their offspring most definitely can.
Fungus gnat larvae survive by eating fungi, organic matter in the soil, and the roots of plants, which can cause damage.
Here’s what finally worked:
Sticky Traps
I actually started using sticky traps while I was trying other methods of eradication. They work really well to capture adult fungus gnats as they’re flying past, but they don’t get to the root (pun intended) of the problem – the larvae.
The sticky traps can’t possibly catch ALL of the adults, so the gnats continue to reproduce, and the problem persists.
Mosquito Dunks
In the depths of the interwebs, after reading about oh-so-many solutions that didn’t work, I came across an article that recommended using mosquito dunks.
Mosquito dunks are small beige discs that are typically used for standing water (i.e. birdbaths). As they dissolve, they release a bacteria that is poisonous to mosquitos – and apparently to fungus gnats!
For the next couple of months (yes, you read that right), every time I watered my plants, I would break off a quarter of a disc, crumble it into my watering can, and let it sit in water overnight to give it time to release the bacteria. I would then water my plants the next day.
While the sticky traps stopped the adult gnats in their tracks, the mosquito dunks killed them early in their lifecycle. I started noticing a difference after the first watering, but it took about 8 tries to completely get rid of the gnats.
During that time, I kept a close eye on the sticky traps and switched them out as needed. This helped me gauge how many gnats were still reaching adulthood and whether I needed to continue the mosquito dunk treatment.
And now, I’m so happy to say that I’m gnat free! I’d really prefer not to deal with this little problem ever again (and I bet you feel the same!), so below are some tips to avoid a gnat relapse.
Easy One Step – How To Get Rid Of Fungus Gnats – 100% Guarantee – Fungus Gnat Prevention
FAQ
How do you get rid of gnats in potted plants?
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Martha Stewarthttps://www.marthastewart.comHow to Get Rid of Fungus Gnats on Houseplants – Martha StewartFeb 25, 2025 — Apply Hydrogen Peroxide While traps help control the adult population of fungus gnats, you still need to treat the eggs and larvae in the soil. Make…
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The Sprucehttps://www.thespruce.comHow to Get Rid of Fungus Gnats in Houseplants NaturallyJul 30, 2024 — The easiest first step is to allow the soil to remain dry for several days before watering again. Both the eggs and the larvae will eventually die o…
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Minnesota Extensionhttps://extension.umn.eduHow to treat pesky fungus gnats in houseplants | UMN ExtensionOct 28, 2024 — How to treat fungus gnats * Dry out the soil. Fungus gnats love moisture, so let the top 1–2 inches of soil dry completely before watering again. T…
Why is my potting soil full of gnats?
Because fungus gnats thrive in moist conditions, especially where there is an abundance of decaying vegetation and fungi, avoid overwatering and provide good drainage. Allow the surface of container soil to dry between waterings. Clean up standing water, and eliminate any plumbing or irrigation system leaks.
Can I put vinegar in my plants to kill gnats?
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Traps:Mix equal parts apple cider vinegar and dish soap in a shallow dish or bowl. Place the trap near your plants where gnats are prevalent. The vinegar will attract the gnats, and the soap will prevent them from escaping.
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Add a small amount of vinegar (like 1 teaspoon per gallon of water) to your watering water every other time you water. This can help kill the larvae in the soil.
Do coffee grounds get rid of gnats?
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Gnats are attracted to decaying matter:Coffee grounds, like other organic matter, decompose and can attract fungus gnats, which lay their eggs in the soil and feed on the rotting material.
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Coffee grounds can increase humidity:The decomposition of coffee grounds can contribute to higher soil humidity, which is another factor that attracts gnats.
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Other methods are more effective:Methods like letting the soil dry out between waterings, using yellow sticky traps, and even introducing beneficial nematodes can be more effective in controlling fungus gnats.
How do you get rid of gnats in soil?
Neem oil, hydrogen peroxide soil drenches, beneficial nematodes, and pyrethrins are all excellent for killing gnats, their eggs and larvae in plant pot soil. You can also use yellow sticky traps to catch and kill flying gnats. Fungus gnats are from the superfamily Sciaroidea, and their larvae feed on the fungus growing in soil.
How to get rid of fungus gnats in houseplant soil?
Here is a list of helpful natural ways to get rid of fungus gnats and kill these bugs in houseplant soil: Hydrogen peroxide to kill off fungus gnat larvae —Make a soil drench with hydrogen peroxide 3% to flush the soil and kill these bugs in the plant soil. This remedy helps kill off gnat larvae in the soil to break their lifecycle.
How do you care for gnats in a houseplant?
Gnat eggs and larvae need moist, damp soil to thrive. So, allow the top 2” (5 cm) of soil to dry out before watering your houseplant. This means you should avoid watering on a set schedule. Always check that the plant soil is partly dry before adding water. Soggy soil only creates an environment where fungus gnats thrive.
How do you stop Gnats from wilting indoor plants?
Larval root damage commonly causes wilting, among other problems. Often, overwatered indoor plants attract gnats. Let the soil dry out between waterings to discourage gnats from making your plants their home. Try easy home remedies like hydrogen peroxide, vinegar, and cinnamon—without killing your plants.
How do you get rid of gnats in a pot?
Here’s what to do. Step 1: Prepare a new pot with fresh, clean soil. Don’t reuse the old soil, as it may be contaminated with gnat larvae or eggs. Step 2: Carefully remove the plant from its pot. Step 3: Brush off as much dirt as possible from the roots. Step 4: Place your plant in the new pot, adding more soil around it as necessary.
Are fungus gnats killing your plants?
If you have a vegetable garden or potted plants in your home, one battle that you may be fighting is with soil gnats, or fungus gnats as they are more commonly known, breeding in the moist soil and eating the delicate plant roots, causing your plants to turn brown and die.