Best Gnat Killer for Indoor Plants – 7 Supreme Picks

You’re in the right spot if you need the best gnat killer for indoor plants. We’ve got ways to rid your plants of pesky fungus gnats, from commercial chemicals to DIY treatments made with pantry staples.

Many people don’t realize indoor gardens have the same risks of pest infestations as the greenery growing outside your house. For example, fungus gnats are one of the most common indoor plant pests. 

Adult fungus gnats are the same small size as a fruit fly and are overall relatively harmless to plants. The issues occur in fact once mature gnats lay eggs on your houseplants and hatch into larvae – baby gnats. Larvae then burrow into the soil and in summary make a full-time all-you-can-eat-buffet on the ground around your plant. They can also snack on your plant roots, in turn leading to plant harm.

Consequently if you’re tired of supporting an entire colony of fungus gnats with your plants, I’ve got several ways to kill them. I’ll also tell you how to detect plant fungus gnat infestations, what causes gnats, and also similarly what to do to prevent future fungus gnat appearances. 

Three of the best methods for how to get rid of gnats in plants are commercial products, DIY solutions, and natural non-harmful treatments. 

My favorite sticky pads for getting rid of gnats include this 60-pack of butterfly pads, or this kit with traps held by pineapples.

But if you have concerns about using sticky traps in your plants, my top gnat killer plant spray has to be Harris Neem Oil for an overall reliable product.

gnats outside in the summer

Here’s a quick list of my favorite best gnat killers for indoor plants:

Keep reading for detailed reviews of each of these products. Then check out the buyer’s guide to understand the presence of gnats on your houseplants and also how to prevent future infestations.

Gnat Killer Product Reviews

There are in fact several methods for getting rid of fungus gnats, from sprays to powders to more physical measures, such as repotting your plants. 

Best Overall – Harris Neem Oil Spray for Plants


Neem oil is above all one of the best ways to treat pest infestations on plants. What I love about Harris neem oil is that it doesn’t just work as a preventative for fungus gnats and other houseplant pests in all stages – egg, larvae, or mature adults. 

In fact this spray is in fact a 3-in-1 insecticide, fungicide, and miticide. It protects from diseases and fungi like rust, downy and powdery mildew, leaf spot, and scab for example.

And also it’s safe for indoor or outdoor use and on all types of plants. Whether it’s blooming flowers, herbs, trees, shrubs, houseplants, edibles, and even your lawn for example.

Key Features:

  • Main ingredient: Neem oil extract 
  • Size: 20 fl oz
  • Application type: spray
  • Uses: treats and prevents diseases, fungi, and insects
  • Treatment length: every seven to fourteen days

Best for:

Harris is the perfect spray for your entire indoor (or outdoor) garden. Whether it’s your food, flowers, or outdoor plants. You can also use this spray to protect your plants from nearly every danger, from bugs to diseases.  

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Best Budget-Friendly Trap – Dwcom Sticky Pad Multi-Pack


Sticky gnat traps can be an affordable and beneficial way to rid your indoor plants of adult fungus gnats. Another additional benefit is that these sticky grip pads can work on other pests. 

These adhesive traps come in packs of 12, 24, 48, and 60 1-inch by 1-inch by 1-inch strips, with the 24 and 60 boxes also available in A2 size.  

The bright yellow color attracts fungus gnats, while at the same time the butterfly shape adds a whimsical decor. Additionally the double-sided adhesive also traps gnats without leaving an odor or being harmful to pets. 

Key Features:

  • Main ingredient: glue
  • Size: 1-inch x 1-inch x 1-inch
  • Application type: Adhesive
  • Uses: traps flying insects and fungus gnats
  • Treatment length: good until covered with gnats

Who’s It For? 

In short these sticky yellow glue traps are the perfect solution for gardeners looking for a hands-off way to stop the appearance of flying insects like mature fungus gnats without having to make frequent applications of chemical treatments. But on the other hand this method does not help treat fungus gnat larvae. 

Best Sticky Gnat Trap –  Proteckter Sticky Traps with Pineapple Stands (2 Pack)


You can use this two-part insect trap system to rid your indoor plants of fungus gnats in their larvae or mature adult form. 

The 1-inch pineapple base has an entrance trap that lets insects enter to get to the bait you add by unscrewing the plastic fruit to access the bait trap in the middle. Therefore once they’re inside, they can’t get out. And the bright yellow color works as an extra attractant. 

And for flying insects, you can attach the 3.1-inch wide, 0.5-inch tall butterfly-shaped sticky pad using the included clip. The non-toxic, non-odor adhesive captures anything that lands on it or flies through the air. When assembled, this attractive whimsical reusable fruit gnat trap certainly stands out at almost five inches tall and three inches wide.

Key Features:

  • Main ingredient: glue (plus whatever you add to the middle) 
  • Size: less than 6-inches tall and 3-inches wide when fully assembled. 
  • Application type: 2-in-1 glue trap plus one-way entry middle trap
  • Uses: attracts and traps gnats, fruit flies, larvae, ants, aphids, and other insects 
  • Treatment length: 30 days or as needed when the trap gets full

Best For:

This two-part gnat killer for indoor plants is useful for any houseplant. However it’s also water-proof and UV-resistant, therefore you don’t have to worry about taking them out of your pots before you put them outside for some yard time. While it will capture most of your flying pest issues, overall it might not in fact fully resolve your infestation if it’s reached the roots stage. 

Best Fungus Gnat Treatment Spray – Garden Safe Houseplant Insect Killer  


This commercial spray kills fungus gnats on contact in all stages, from larvae to mature flying pests. It also works on beetles, aphids, ants, caterpillars, mites, mealybugs, and additionally other harmful bugs. 

This botanical insecticide is also safe to use on your edible foods until you harvest them. But on the other hand be sure to wash any food before eating it.

Key Features:

  • Main ingredient: Pyrethrums with Canola oil
  • Size: 20 ounces  
  • Application type: spray
  • Uses: Treats insect infestations of gnats, aphids, and other larvae and flying pests by killing on contact
  • Treatment length: up to 8 weeks

Best For:

This botanical spray is best when you notice an active larvae infestation but less mature gnat bugs. Since it requires coming into contact to work, it’s therefore more difficult to apply this spray to flying gnats.

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Top Granulated Chemical Gnat Killer – Bonide Systemic Houseplant


You can use this chemical pesticide on your indoor container plants to treat the infestation of fungus gnats and other harmful pests. 

The granules are ready to use to treat fungus gnats at any stage of their development. You can measure out the appropriate application based on your plant’s size. 

As an easy-to-apply granule, there’s no mess or residue from sprays for example. And because there’s no odor, it’s safe to use indoors in fact. 

Key Features:

  • Main ingredient: Bonide
  • Size: 1.3 pounds 
  • Application type: granules
  • Uses: Prevents damage from insect infestations of gnats, aphids, whiteflies, and other flying pests
  • Treatment length: up to 8 weeks

Best for:

This granular chemical gnat killer is consequently for any indoor container-grown houseplants experiencing problems with fungus gnats that other treatment methods haven’t eliminated.

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Top Natural Mineral to Kill Gnats – Diatomaceous Earth


Diatomaceous earth is a fine powder created out of fossilized algae or other organic matter and natural minerals like silica. 

Adding this mineral to your soil causes the gnat larvae to dry out and subsequently get cut down by the sharp silica. It will also cause the earth to be inhabitable by future gnat infestations.

You can sprinkle food-grade diatomaceous earth into the potting mix before you add your plants. Or alternatively for plants already established in a pot, add the powder directly to the top of the dirt around the plant.  

Key features:

  • Main ingredient: fossilized algae and silica
  • Size: 10-pound bag (smaller bags are available in 2 and 5 pounds)
  • Application type: powder direct applied to the soil
  • Uses: treats gnat larvae infestations
  • Treatment length: varies

Best for:

Diatomaceous earth is best to use when starting plant specimens in new pots. But it can also be useful if you’ve noticed a larva infestation in the soil of your existing plants. However, this option doesn’t do much to treat mature flying fungus gnats unless they land on the ground and feed. So therefore use this solution in addition to other methods.

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Best for Alternate Gnat Killer Source – Katchy Automatic UV Light with Fan


This Katchy combo uses three methods to lure and kill fungus gnats. First, this electric machine starts with a fan that uses airflow to pull bugs into the machine.

Inside there’s a UV light to help attract flying bugs closer to the fan’s current. Also as the gnats get sucked into the machine, they then get pushed down onto a sticky board that in the end keeps them trapped. 

You can set the device up near your plants. When you turn the lights off, as a result the fan and UV light will automatically turn on and go to work. 

Key features:

  • Main ingredient: UV light
  • Size: 5-inch x 5.5-inch x 9-inches
  • Application type: Automatic
  • Uses: attracts and kills flying insects
  • Treatment length: glue boards last one month

Best for:

This gnat killer solution is for anyone who is looking for a way to get rid of mature fungus gnats that fly around your plants without having to apply chemicals or sticky traps. Once it’s dark, the Katchy automatically turns on and runs until it senses light again. Running it consecutively for three days should eliminate all mature fungus gnats and other pests. 

Best DIY Gnat Killer Application – Water and Hydrogen Peroxide

You can in fact make a safe, affordable gnat killer using a common product from your medicine cabinet – hydrogen peroxide. 

Firstly combine one part peroxide with four parts water in a spray bottle. To clarify, a part can be any size unit, as long as it’s used for both ingredients. Depending on your bottle size, you can use a ½ or 1 cup measurement.

You should only apply this gnat killer solution to your plants once the soil medium dries out. Don’t be alarmed if you hear an odd popping sound once the peroxide settles into the soil. A great thing about using peroxide above all is that it breaks down in the ground after killing the larvae. All without causing harm to your plants.

In most cases, a single treatment should kill all the gnat larvae. But severe infestations can need a second dose. And this solution might not rid your plants of adult fungus gnats, so it’s best as an additional treatment with another method, like sticky pads.

Non-Harmful Ways to Get Rid of Fungus Gnats

If you want to get rid of fungus gnats without killing them, there are several non-harmful methods. In short one of the best ways to eliminate fungus gnats is to eliminate the conditions they need to thrive, such as wet soil for example.

Control Watering to Prevent Soggy Soil

Most importantly give your plants enough time for the top two inches of soil to dry out between waterings. For instance too much water too often can encourage the roots to rot and the growth of algae and mold in the ground.  

In summary never water your plants without first testing the soil’s dampness. Poke your finger into the dirt along the pot’s rim until your second knuckle is covered. If your finger comes out clean and without any traces of soil, it’s safe to water. Otherwise, skip the day. 

In fact using a bamboo stick can also be an appropriate method of moisture testing. Insert the stick inside the pot and slowly pull it out and examine it. Bamboo wood will actually darken in color as it encounters liquid, in turn allowing you to test the soil’s moisture depth. Wet soil will cling to the stick, leaving behind residue. 

I personally steal these disposable wood skewers from my husband’s grill (shoosh, don’t tell my secret!).

A third and more technical way to check the moisture level in the dirt is with a moisture meter. This one is my fav! First it tests the soil’s pH, then moisture content, and also sunlight exposure to get the perfect growing conditions to prevent fungus gnats from all indoor houseplants.

Add Potato Slices to the Soil

potato slices white background

One way to rid the soil of gnat larvae is to cut a potato into wedges. Then, insert one – or in fact several – of these slices slightly down into the dirt around your plants and let them sit for a few days. 

If larvae are present inside the soil, they will subsequently rise to feed on the potato. After that, maybe three or four days, discard the potato pieces.

Moreover you can also flip the wedges over to see how many gnats you’ve collected and determine if you need to use more slices.  

Repot Your Plant and Discard Infected Soil

Above all the best way to ensure you get rid of all the fungus gnat infestation is to remove your plant from the infected soil and pot and put it into a fresh one. 

Once you take your plant out of its current pot, make sure to toss away the damaged growing medium. This is so that gnat larvae can’t infect your other plants. Do not add this soil to your compost or back where it will encounter other plants. 

Then rinse the roots of your plants before you transplant these specimens into a new pot with a fresh growing medium. Meanwhile when dealing with sensitive roots, you can shake the excess soil free rather than rinse the roots. Subsequently if you want to reuse the same pot, clean it thoroughly to remove decay or old dirt. 

Gnat Killer Product Buying Guide

Knowing how to eliminate fungus gnat infections is only half the battle. There’s no point in getting rid of the insects if you’re not going to make any changes to prevent future infestations. 

Therefore, it helps to understand what conditions encourage fungus gnat presence. Then, you must know how to identify fungus gnats and their larvae to provide your plants with the correct treatment. 

What Causes Gnats?

watering plants outside

The biggest question about how to kill gnats should be what attracts gnats. Understanding the conditions they like means you can work on preventative measures. 

Fungus gnat larvae enjoy moist soil where they can feed on decaying matter and fungi. But they will also start feeding on the plant roots. 

So, conditions that attract fungus gnats are:

  • Waterlogged soil that’s been overwatered.
  • Bright light.
  • Wet, warm climates.
  • The presence of mildew and mold.

Gnat larvae thrive in rotting, decaying conditions. 

How to Test for Fungus Gnats

Not sure if fungus gnats cause your plant’s foul symptoms? Wondering if the insects you see near or on your plants are fungus gnats and not other household insects like aphids or black flies? 

Firstly examine the soil closely and search for signs of insects, black flies, or flying insects near the plant or the earth. After that, look for white gnat larvae – small white specks – resting on the soil or barely under the surface. Meanwhile look at the overall health of your plant. 

Fungus Gnat Infestation Symptoms

Specimens dealing with infestation typically show physical signs like stunted growth of young plants and wilting, discolored, or shedding leaves. 

If in fact left untreated, gnat larvae can work their way down to the root system. This can lead to compromising the health of the entire plant as the roots are how the plant gets nutrients to stay hydrated. 

Damaged roots can also cause the leaves and stem to wilt or wither. It can additionally result in leaves that lose color or prematurely age with spots or wrinkles. Fungus gnats can even cause leaves to fall off early. So finding mature and young leaves shedding, you’re likely dealing with gnat larvae.  

FAQ About Gnat Killer for Indoor Plants

What is the fastest way to get rid of fungus gnats in houseplants?

The fastest way to get rid of fungus gnats in houseplants is to repot your houseplant with fresh soil after rinsing or dusting off the plant to remove any gnats.

How do I get rid of gnats in my potting soil?

Before taking drastic measures like chemicals, try a simple solution of a quart of water with a tablespoon of dish soap. Then try our other gnat killer options listed above.

How do you get rid of fungus gnats without harming houseplants?

The best way to get rid of fungus gnats without harming your houseplants is by using sticky traps, preferably yellow, to attract the bugs.

It’s Time for Fungus Gnats to GO!

Altogether fungus gnats are one of the most common indoor infestations you can experience. Luckily, it’s quite easy to rid your plants of these pesky bug infestations. You can treat your infected plants with natural ingredients, powders, sprays, sticky traps, lights, and non-harmful methods like repotting. You can also manually removing all signs of infestation for instance. In my opinion above all can’t go wrong with neem oil spray, overall this is an essential. Additionally, a decorative and functional option could be the pineapple sticky pads, furthermore why not make a statement! Whatever your choice, you know there are plenty of options out there.

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Sara Trimble
Sara Trimble was the lady who could kill a cactus. Today, she’s the fun and fabulous expert plant mom who rocks at growing the coolest, trickiest plants. Her favorites to grow are orchids, roses, succulents, and luscious vines. Sara has grown – and killed – hundreds of plants and she shares her green-thumb successes and failures to help other plant murderers discover correct plant care. In her spare time, she raises four kids, two dogs, and a husband.

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