In this article, how to get rid of fungus gnats in Houseplants, we will explore some of the best methods for controlling a fungus gnats infestation, from methods like using diatomaceous earth, neem oil spray, essential oils, and many more.
I will also fill you in on some simple yet very effective preventative measures you can take to avoid re-infestation.
If you’re a plant lover like me, you know how frustrating dealing with pesky fungus gnats in your house plants can be.
These tiny insects can be a real nuisance and can cause damage to your plants if left unchecked. But don’t worry – plenty of simple yet effective ways to eliminate fungus gnats in your houseplants.
Ready to learn how to keep your houseplants healthy and free from pesky fungus gnats!?
Let’s get started.
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How to Get Rid of Fungus Gnats in House Plants
What are Fungus Gnats?
Gnats are small flies (similar to fruit flies but with long legs). These tiny flies are strong fliers that belong to the same family as mosquitoes and flies.
They are attracted to moist environments and organic matter and often infest houseplants.
Gnats lay their eggs in moist soil, where the fungus gnat larvae feed on organic matter and plant roots. This can lead to plant damage and even death if the infestation is not dealt with quickly.
Signs of a Fungus Gnat Infestation in Houseplants
The most obvious sign of these little insect pests is the presence of flying insects around the plants. You may also notice small, black flies crawling on the soil surface or around the base of the plant.
Other signs of a gnat infestation include yellowing or wilting leaves, stunted growth, and a weakened root system.
Signs of Fungus Gnat infestation:
Presence of adult gnats
If you see small, black flying insects around your plants, they may be fungus gnats. Adult fungus gnats are attracted to light and fly around windows or light fixtures.
Wilting or yellowing leaves
Fungus gnats can damage the roots of your plants, which can cause the leaves to wilt or turn yellow.
If your plants are not growing as quickly as they should be, it could be a sign of root damage from fungus gnat larvae.
Poor soil quality
Fungus gnat larvae feed on organic matter in the soil, which can cause the soil to become compacted and low in nutrients.
Fungus gnats thrive in moist environments, so if your soil is constantly wet or overwatering your plants, you may be providing the perfect breeding ground for them.
How did I get fungus gnats in the first place?
There are several ways that fungus gnats can make their way into your home and infest your plants.
The most common way fungus gnats can get into your house is as stowaways in a new houseplant with infected potting soil.
Common causes of fungus gnat infestation:
Fungus gnats can be introduced to your plants through infected potting soil. If you purchased soil already infected with fungus gnat larvae, the larvae can quickly grow and multiply in your plant’s soil.
Overwatering your plants can create a moist environment that is ideal for fungus gnats to thrive in. The larvae feed on organic matter in the soil, and moist soil provides the perfect breeding ground for them.
Plants with poor drainage can also create a moist environment attractive to fungus gnats.
If water is allowed to sit in the bottom of the pot or if the soil is not aerated correctly, it can lead to root rot and a buildup of moisture that can attract these insect pests.
Contaminated plant material
Fungus gnats can also be introduced to your home through contaminated plant material, such as cuttings or new plants.
If the plants or cuttings were already infested with larvae or eggs, they could quickly spread to your other plants.
Open windows and doors
Fungus gnats are attracted to light, so leaving your windows or doors open can easily make their way into your home and infest your plants.
Getting Rid of Fungus Gnats Can Be Challenging
Fungus gnats are super challenging to eliminate. And the more houseplants you have, the worse the fungus gnats can get!
The fungus gnat adults fly or jump from one plant to the next, laying eggs wherever they find damp soil.
The good news is that the adult fungus gnats only live for a few days! The bad news is that you will have to deal with the fungus gnat larvae to get rid of your fungus gnat problem for good.
The Life Cycle of a Fungus Gnat
Understanding the life cycle of a fungus gnat is essential in effectively controlling and preventing an infestation.
The entire life cycle of a fungus gnat can take anywhere from two to six weeks, depending on environmental conditions like temperature and moisture levels.
It’s important to note that fungus gnats can have multiple generations per year, and infestations can quickly grow if left unchecked.
Understanding a fungus gnat’s life cycle:
Egg: The life cycle of a fungus gnat begins with an egg laid in moist soil by an adult female gnat.
Larval stage: The egg hatches into a small, legless larva that feeds on organic material in the soil, including plant roots.
Fungus gnat larvae are small but visible to the naked eye. They typically measure up to 1/4 inch in length and (gross) have a distinct shiny black head and transparent body.
Pupae: After feeding and growing for several weeks, the larva will pupate and form a cocoon in the soil. The pupal stage lasts for several days to a few weeks.
Adult: The adult fungus gnat or emerges from the cocoon and begins to fly around, searching for a mate and a suitable place to lay eggs. Adult fungus gnats are small, black flies about 1/8 inch in length. (source)
How to Get Rid of Fungus Gnats in Houseplants
1. Insecticide (Safe for indoors)
First things first. The first thing you’ll want to do is cut down the number of adult gnats.
Just one fungus gnat can lay as many as 200 eggs quickly. Cutting the number of adult fungus gnats is only half the battle, but it’s the best place to start.
Insecticides with the active ingredient Pyrethrin-based insecticides are a common insecticide derived from chrysanthemum flowers. They effectively kill a wide range of insects, including fungus gnats, and are commonly used in outdoor and indoor settings
This insect killer from Garden Safe is the first product I reached for. It killed many adult gnats flying around, which helped a ton, but the smell is pretty strong.
2. Neem Oil Spray
Neem oil is very effective in treating adult fungus gnats.
Mix a neem oil solution with water (Follow the label’s directions). Mix well.
Using a clean spray bottle, spray all plant surfaces (including the undersides of leaves) and soil until the entire plant and dirt are completely wet.
Neem oil is another good option to treat adult fungus gnats.
You can use a pre-mixed neem oil spray or you can purchase neem oil mix it with water, and put it in a spray bottle.
Spray all plant surfaces (including the undersides of leaves) and soil until the entire plant and dirt are completely wet.
Neem oil is safe for outdoor and indoor use. Repeat every two weeks.
Related article: The Best Neem Oil for Houseplants
Insecticidal soap is a safe and effective way to kill gnats and other pests on houseplants.
Spray the solution on the leaves and soil of your plants, making sure to cover the entire surface. The soap will suffocate the gnats and their larvae.
I purchased this insecticidal Soap and used it about once a week to lessen the number of adult gnats. It works well to kill adult gnats, but I will warn you -the smell isn’t my favorite.
You can also make your own insecticidal soap by mixing 2.5 tablespoons of vegetable oil and 2.5 tablespoons of pure liquid soap with 1 gallon of distilled water
4. Hydrogen Peroxide Solution
Hydrogen peroxide is a natural disinfectant that can kill fungus gnats and prevent them from laying eggs in the soil.
When I first heard about using this hydrogen peroxide mixture to kill fungus gnats, it put me off.
As a bonus: Watering plants with this solution brings extra oxygen to your plant roots, which my plants seemed to love!
If you want to use hydrogen peroxide to control fungus gnats, it’s important to mix it properly to ensure its effectiveness and avoid damaging your plants.
How to mix hydrogen peroxide mixture:
Mix one hydrogen peroxide with three parts water and pour the solution into the soil around your plants. The peroxide will kill the larvae and disinfect the soil.
To mix hydrogen peroxide using a gallon of water, you’ll need a clean watering can and a bottle of 3% hydrogen peroxide.
Then, add one tablespoon of hydrogen peroxide to the water, and mix well.
These little “bits” are the bomb! Fungus gnats diminish quickly when I bring out the mosquito bits! Don’t let the name fool you. These tiny granules control Fungus gnats, as well as mosquitos! Just sprinkle the mosquito bits on top of the soil and water to activate.
They work great!
Mosquito Dunks are a form of biological control that uses the larvae-killing bacteria Bacillus thuringiensis. Bacillus thuringiensis is harmless to humans and animals but fatal to the larvae of flying insects, including mosquitoes, fruit flies, and fungus gnats.
To use mosquito dunks, fill up a gallon jug or large watering can with clean water and let the dunk soak in it overnight. After removing the leftover dunk (which can be reused), you may then utilize that same water for your houseplants.
You would see optimal results from mosquito dunks when bottom-watering plant baths, especially if you have multiple plants to treat – keep repeating until those pesky fungus gnats are gone!
The Best Natural Ways to get rid of Fungus Gnats
7. Apple Cider Vinegar Trap
You can make an apple cider vinegar trap using vinegar, water, and dish soap.
How to make apple cider vinegar traps:
To make your DIY trap for these pesky gnats, mix a cup or two of water with a few tablespoons of apple cider vinegar and a few drops of dish soap in a shallow container or small saucer.
Cover the top with plastic wrap and poke small holes in the plastic for best results.
This mixture will attract the fungus gnats and kill them. Repeat every couple of days.
If you don’t want to make a vinegar trap, I found this small stainless steel bug trap that works for fruit flies and fungus gnats.
Yellow sticky cards or traps are a very effective way to trap and kill these houseplant pests!
These tiny insects are attracted to yellow, then get stuck and die.
You will be shocked at the number of gnats you will capture with these yellow sticky traps! It’s just crazy!
Diatomaceous earth is a natural and effective way to control various insect pests, including fungus gnats.
It comprises the fossilized remains of tiny aquatic organisms called diatoms, a fine, powdery substance applied to the soil.
When diatomaceous earth comes into contact with insects, it causes them to dehydrate and die. It is a physical mode of action rather than a chemical one, which makes it a safe and natural alternative to chemical insecticides.
Steinernema feltiae is a type of microscopic roundworm that is used as a biological control agent for a variety of soil-dwelling insects, including fungus gnats.
These tiny worms are a natural predators of many soil-dwelling insects and can be an effective alternative to chemical insecticides.
When applied to the soil, Steinernema feltiae infects the larvae of fungus gnats and other pests, releasing bacteria that kill the larvae within a few days. This can help to control pest populations and reduce the damage they cause to plants.
Cinnamon is a natural fungicide and insecticide that can kill soil gnats and prevent them from laying eggs in the soil. Sprinkle cinnamon powder on the top layer of soil around your plants, covering the entire soil surface.
Cinnamon is a popular natural remedy for controlling fungus gnats in houseplants.
Cinnamon is believed to contain toxic compounds to the larvae of fungus gnats, making it an effective and natural way to control infestations.
To use cinnamon on your houseplants, sprinkle a small amount of ground cinnamon on the top inch of soil around the base of the plant. The cinnamon will help kill fungus gnats’ larvae and prevent further infestations.
12. Essential Oils
Essential oils can be an effective and natural way to control fungus gnats in houseplants.
Many essential oils contain toxic compounds to insects, making them a safe and natural alternative to chemical insecticides.
To use essential oils to control fungus gnats, mix a few drops of the oil with water in a spray bottle, and spray the soil around your plants.
You can also add a few drops of the oil to a cotton ball and place it near your plants to help repel adult fungus gnats.
Some of the most effective essential oils for controlling fungus gnats include neem, peppermint, and tea tree oil.
These oils can help kill fungus gnats’ larvae and prevent adult insects from laying eggs in the soil.
13. Remove the Fungus Gnat Larvae
I avoided this step because I didn’t want to deal with the mess. But I have to tell you- Removing the infested soil is key!
How to remove fungus gnat larvae from houseplants
Remove the top inch of potting soil (dispose of the old soil in an outside garbage container) and replace it with brand-new potting soil. Replacing the top layer of soil will remove fungus gnat eggs and larvae.
I often transplant the entire plant, replacing all of its soil. That way, you can be sure you’ve removed all the infested soil.
14. Control Soil Moisture
Fungus gnats love moist soil. That said, it’s imperative to control the moisture on the soil’s surface.
The two best methods to control too much moisture on the plant soil are bottling water and adding soil covers.
–Water Plants From the Bottom
Bottom watering your plants will make it easier to maintain dryer topsoil without risking the plant’s overall health.
Bottom watering plants is immersing the pot into a tray of room temperature water, allowing the roots to absorb moisture from drainage holes.
It’s an excellent way to keep the surface of the soil with the extra benefit of watering houseplants without overwatering them or risking stem and leaf rot.
–Use Soil Covers
Covering the top layer of the soil gives the houseplants a nice added/decorative touch too!
*Never leave the potting mix in an open bag as fungus gnats, as that’s a perfect breeding ground for fungus gnats. Instead, when I purchase new potting soil, I transfer it to a bid with a tight-fitting lid.
Related article: How to use LECA Clay Pebbles
The Katchy indoor insect trap kills fruit flies, gnats, and mosquitos. (doesn’t work on houseflies)
It uses a UV light, a powerful fan, and a sticky glue board to eliminate fungus gnats, fruit flies, and other small bugs.
Simply place it in your home, kitchen, or office to eliminate annoying pests in no time! It’s like a miracle!
How to Prevent Fungus Gnat Infestation
Preventing fungus gnats from infesting your houseplants is easier than trying to get rid of them once they’re already there.
Here are some practical ways to prevent fungus gnats from becoming a problem:
Keep the top layer dry.
Fungus gnats don’t like dry soil. That said, do everything possible to keep the top inches of soil dry by using soil covers and bottom water and avoiding overwatering.
Fungus gnats thrive in moist soil, so avoiding overwatering your plants is essential.
Ensure the soil has dried out slightly before watering, and don’t let your plants sit in standing water.
Use well-draining soil
Good drainage is key to avoiding a fungus gnat infestation; using a well-draining soil mix can help prevent soil from becoming waterlogged and create a favorable environment for fungus gnats.
Proper drainage hole
An adequate drain hole is crucial for the health and well-being of potted plants. When a plant is in a pot without proper drainage, excess water can accumulate in the soil and suffocate the roots, leading to rot and other problems.
Choosing pots with adequate drain holes is essential to ensure that your potted plants have proper drainage.
These holes allow excess water to escape from the soil, preventing it from waterlogging and damaging the roots.
Ensure proper air circulation.
Good air circulation can help keep the soil dry and prevent fungus gnats from laying eggs in the soil.
You can achieve this by placing a fan near your plants or by opening a window.
Inspect new plants
Before bringing new plants into your home, inspect them for any signs of pest infestations. This can help prevent fungus gnats and other pests from spreading to your other plants.
Continue to use yellow sticky traps.
Sticky traps can effectively catch adult fungus gnats and prevent them from laying eggs in the soil. These can be purchased at garden centers or online.
Implement natural pest control methods.
Natural pest control methods, such as diatomaceous earth, beneficial nematodes, or cinnamon, can help prevent and control fungus gnat infestations without using harmful chemicals.
Isolate infected plants.
If you notice that one of your plants is infected with a pest or disease, it’s a good idea to isolate infested from your other plants as soon as possible.
Removing an infested plant can help prevent the infestation from spreading to your other plants and causing widespread damage.
When isolating an infected plant, moving it to a separate area of your home or garden, away from your other plants, is best.
You may also want to consider covering the plant with a plastic bag or cloth to prevent pests from escaping and spreading to other plants.
Final Thoughts: How to Get Rid of Fungus Gnats in Houseplants
Controlling pesky fungus gnats in your houseplants is essential for the health and well-being of your house plants.
Infestations can lead to stunted growth, yellowing leaves, and even plant death.
By following preventative measures, such as avoiding overwatering and using well-draining soil, can make a huge difference.
If you notice an infestation, natural pest control methods, such as diatomaceous earth, beneficial nematodes, cinnamon, or essential oils, can help control the infestation and prevent further damage.
Remember to also take steps to protect the health of your plant’s root systems, such as ensuring proper drainage and avoiding overwatering.
Healthy plants with robust root systems can better resist pest infestations and other problems.
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