How To Get Rid Of Fungus Gnats In Houseplants For Good?

Use a hydrogen peroxide solution to instantly kill larvae or apply neem oil as a natural remedy that effectively targets both adult gnats and larvae.

Indoor gardening enhances your home with greenery but can invite fungus gnats if soil moisture isn’t managed. Overwatering creates a perfect breeding ground for these pests. Our guide offers effective solutions, from hydrogen peroxide sprays to natural remedies like neem oil and sticky traps, to eliminate fungus gnats and keep your houseplants thriving.

Discover how to protect your indoor garden from these pesky intruders with our concise, expert tips.

Key Takeaways

  • Use hydrogen peroxide spray or neem oil for instant and natural gnat elimination.
  • Control soil moisture with proper watering to prevent gnat breeding.
  • Apply sandy soil on top to create an inhospitable environment for gnats.
  • Introduce predatory nematodes for biological control of gnat larvae.
  • Ensure good air circulation and humidity control to deter gnats.

Understanding Fungus Gnats

You may be wondering about fungus gnats. Bearing the name, it’s not wrong if you ever think they are a fungus that infects plants.

However, the following “gnats” name may confuse you as it refers to insects. A fungus gnat is a fly with a soft body and dark color. Depending on the species, it could be black or has a touch of terracotta.

how to get rid of fungus gnats in houseplants
Understanding Fungus Gnats

The “fungus” name comes from their favorite meals as they feed on fungi. They also chew grass clippings, compost, and organic mulch.

To better understand how to get rid of fungus gnats, you must know fungus gnats life cycle and habits.

1. Importance of Houseplant Care

Those who have limited space in their home or even live in an apartment will prefer houseplants to grow. Depending on the species and size, they can grow in pots or hanging baskets.

Many create indoor gardens to provide greenery that can give a therapeutic effect to the owners.

Others grow them to improve indoor air quality as some houseplants, such as spider plants and Boston fern, can filter air well. Besides, they are generally low-maintenance.

Unfortunately, many become careless in their treatment. They ignore the factors that affect the growth of houseplants, like soil moisture, light exposure, and humidity.

Soil moisture is crucial to ensure the roots are well-hydrated. Moreover, it helps break down organic matter, which plants will use to thrive.

how to get rid of fungus gnats in houseplants
Importance of Houseplant Care

Contrary, overwatering is also a problem as it can trigger root rot and fungus gnats larvae infestation due to high humidity. Once it happens, you can only repel fungus gnats with chemical treatment or biological control, for instance, releasing predatory nematodes that will kill the gnats larvae.

Hence, good drainage holes are necessary for water flow through the soil.

In addition to soil moisture, you must know the light requirements of your plants. Even though they grow indoors, some of them require full sun. So, you better find a south-facing spot to provide adequate sunlight exposure.

This is important as the sun helps plants carry out photosynthesis, a process to produce food. But remember, this requirement really depends on the plant species.

Those who need shade location will grow leggy or droop if they receive too much sunlight.

2. Life Cycle of Fungus Gnats

If you want to know how to get rid of fungus gnats, understanding their life cycle is a must. It can guide you to find the best chemical, physical, or biological control to remove them entirely from your houseplants.

There are four fungus gnats’ life cycle stages they need to go through before turning into adult ones. The first one is eggs.

Female fungus gnats will lay their eggs on a damp potting mix rich in organic matter, like compost.

how to get rid of fungus gnats in houseplants
Life Cycle of Fungus Gnats

Organic matter will provide nutrients for the fungus gnats larvae to eat. Depending on the temperature, these eggs will hatch into larvae in only about 3 days when the temperature is around 75ºF.

The warmer it gets, the faster eggs pop up.

Now, you will have fungus gnats larvae for 10 days. This stage is the most crucial as these fungus gnats larvae are predators that instantly ruin your houseplants.

Initially, they will feed on nutrients from moist, organically-rich soil where the plants grow.

They will spread faster if the pots do not have good drainage, causing the soil to be constantly wet. This condition favors the larvae to dig into delicate young plant roots, resulting in damage, plant stunt, and even death.

After that, these larvae will transform into oblong pupae for 4 days before developing into adult ones. The whole cycle will take approximately 17 days.

3. What Months are Fungus Gnats Most Active?

Fungus gnats can reproduce year-round.

However, their eggs will likely hatch faster under warmer temperatures along with high humidity. They are also most active in certain months, such as March, September, and October.

In addition, some also argue that fungus gnats favor summer the most as it can provide warm and damp conditions for them to speed up reproduction. Spring, summer, and fall temperatures are warmer but cool, precisely what the fungus gnats like.

how to get rid of fungus gnats in houseplants
March, September, and October Are Months That Fungus Gnats Most Active

These pests love temperatures around 75ºF to 80ºF and do not cope with cold.

Nonetheless, they also do not withstand hot temperatures. Hence, you can treat fungus gnats with heat treatment, such as baking soil infected by gnats at 350ºF.

We also recommend soil solarization by wrapping the ground with transparent polyethylene in the summer. This heat treatment is pretty effective as the soil solarization will trap the high temperature, causing the eggs, larvae, and adults on the soil to die.

You can also kill fungus gnats naturally by letting them freeze at any temperature below 60ºF.

4. Habitat and Breeding Grounds of Fungus Gnats

Instead of low humidity, fungus gnats prefer potted plants that grow in moist conditions for their habitat and breeding grounds.

Hench, you will mostly find them around moist soil or potting mix. It will worsen if you have houseplants that grow in organically-rich soil with compost or mulch. They will rapidly spread because organic matter is a food source for the fungus gnats larvae.

how to get rid of fungus gnats in houseplants
Habitat and Breeding Grounds of Fungus Gnats

In addition, these nutrients will increase the chances of mold growing, another favorite meal of fungus gnats you provide in your indoor garden.

Not only gnats larvae like these molds, but adult flies also feed on them. But remember, the larvae are the troublemakers since they can damage the plant roots and thus cause stunted growth.

Moreover, as fungus gnats are weak fliers, they will like to hang around longer in your potted plants, worsening the condition.

Apart from your indoor garden, they will also inhabit several other indoor areas with high humidity, such as bathrooms, kitchen sinks, laundry areas, and crawl spaces.

You better arrange sticky traps if you want to eliminate the adult ones.

Nonetheless, we highly recommend removing fungus gnats naturally by applying biological control with predatory nematodes that can be the best way to get rid of larvae and the adults all at once. These beneficial nematodes will enter the mouth or anus of gnats and kill them.

Problems Caused by Fungus Gnats

Fungus gnats are the culprits behind stunt growth in plants. They commonly infect seedlings and young plants whose roots and parts are soft and easy to chew by the larvae.

While all plants are their targets, some become their favorite food, such as African violets, carnations, geraniums, and poinsettias.

how to get rid of fungus gnats in houseplants
Problems Caused by Fungus Gnats

Regarding the damage caused by these insects, you should not be fooled by their short life cycle.

Though they only last for 18 to 30 days, adult female fungus gnats can lay around 200 eggs at once. This cycle will continue if you do not notice that your indoor houseplants are infested with gnats, eventually damaging your plants.

In small numbers, the fungus gnats will only annoy you while watering your houseplants. You will notice tiny, grayish insects flying around potted plants once the water flows through the soil.

But that’s different in large numbers. You can spot signs of wilt and yellowing leaves, just like root rot symptoms.

Furthermore, you will see slower growth of your plants along with those symptoms. It is caused by the gnat larvae feeding on the delicate roots.

If you do not get your plants treated immediately, the roots will be highly damaged and your plants may die. Therefore, drying out soil between watering is always favorable to prevent this issue.

Prevention Methods to Get Rid of Fungus Gnats

The key to knowing how to get rid of fungus gnats in houseplants naturally is understanding how to treat them properly since the cause of the infestation is poor maintenance.

Finding an ideal prevention method is always better than choosing the best home remedy to eliminate these culprits.

Here are some ways to prevent fungus gnats from inhabiting your plants as well as removing them naturally:

1. Proper Watering Techniques

The trouble with fungus gnats always starts with poor watering and drainage.

Improved drainage will cause water to be trapped in your soil, making it constantly wet. This condition favors fungus gnats to lay and hatch their eggs because they are moist.

how to get rid of fungus gnats in houseplants
Proper Watering Techniques

Not only that, but the absence of drainage holes also causes standing water. 

In addition to drainage, overwatering keeps the soil damp for an extended period, creating a favorite habitat for fungus gnats to stay longer.

Therefore we recommend paying attention to your watering techniques and ensuring having suitable drainage holes according to the size of your pots and plants.

We love to allow the soil to dry out between watering to avoid wet conditions that can invite fungus gnats to inhabit. Besides, we also prefer bottom watering as it prevents the soil surface from getting damp, keeping low humidity, yet adequately hydrates the roots.

You can add a bowl of water and then put the pot inside it. Let it sit until the water doesn’t seem to decrease anymore, then take the container out.

2. Soil Selection and Preparation

Besides moist soil and rich potting mix, fungus gnats love to hang around plants that grow in soil rich in organic matter. These nutrients are beneficial for them to feed their larvae.

In general, they will like flying around composted potted plants because it is loaded with nutrients and moisture, a perfect combo for gnats to reproduce faster.

how to get rid of fungus gnats in houseplants
Soil Selection and Preparation

We usually use a trick to solve this problem by adding sandy soil to the top layer of soil.

The characteristics of sandy soil with low humidity will make the gnats fungus reluctant to stay in your houseplant’s pots. Apart from that, this soil also has the potential to naturally kill the fungus gnats in houseplants.

You can add compost on the top layer evenly, then add ¾ inch layer for the sand to dry the top surface. However, for this method, we recommend that it be accompanied by bottom watering so that the soil surface is not too wet.

3. Soil Covers and Barriers

You can study determining methods on how to get rid of fungus gnats in houseplants from the factors that support their growth. They love plants, soil moisture, and organic matter, so you must adjust them to be able to remove these troublemakers.

Well, it’s sometimes challenging because our plants need moist soil, but that will invite fungus gnats. However, this can be arranged by purchasing pots with good drainage.

how to get rid of fungus gnats in houseplants
Soil Covers and Barriers with Horticultural Sand

To overcome this further, you can create soil covers! We have a great recipe to make one using horticultural sand. Add about ¼ inch of this horticultural sand on the top layer to reduce moisture.

This condition will cast away the female fungus gnats from laying their eggs on the soil.

You can add more if the humidity in your house is high. Sand has the excellent characteristic of absorbing moisture, thus making the soil conditions in your pot unfavorable for the gnats to inhabit.

4. Plant Selection and Placement

If you are growing seedlings or young plants in your indoor garden or greenhouse, you must be aware of fungus gnats. The delicate roots and some parts of the plant are easy to chew, making their fungus gnats favorites!

Apart from that, some potted plants, like African violet and geraniums, are two of their preferable habitats.

Plant Selection and Placement Plant Near South-Facing Window
Plant Selection and Placement Plant Near South-Facing Window

We highly suggest paying attention to humidity and drainage when planting them or other young plants. You must also consider having them near your south-facing window, where the sun shines brighter than any other spot.

Fungus gnats hate bright light conditions, so placing your potted plants near your window boxes is an option to get rid of them for good!

Nonetheless, we do not recommend arranging one around plant lights as the adults are attracted to these plant lights. So, you better close all the doors and windows at night to avoid them entering the house and ruining your plants.

5. Air Circulation and Humidity Control

Humidity is one of the factors that influence the success of pest control in eradicating fungus gnats. As you already know, fungus gnats are attracted to moist soil.

Hence, it is crucial to lowering the moisture so the soil becomes an unsuitable place for gnats to reside.

One of the best ways is to regulate air circulation. You can consider placing the plants near windows, especially south-facing ones, so they are exposed to the hot sun. However, make sure your plants do need full sun to thrive.

Humidity Control To Eradicating Fungus Gnats
Humidity Control To Eradicating Fungus Gnats

We also suggest opening your doors in the morning to allow your houseplants to breathe. Moreover, you can create spaces between plants, so they don’t share moisture.

It is also beneficial for the plants just in case one needs to go through plant quarantine after being infected by diseases or fungus gnats.

In addition, install a fan if the humidity conditions are high. Consider growing plants in hanging baskets, as it gives the roots and bottom soil better access to oxygen.

Remember to buy containers with drainage holes!

6. Cleaning and Maintenance of Plant Containers

Many houseplants owners may need to realize how important it is to clean up their plants’ pots, containers, or hanging baskets to avoid pests and diseases.

Regarding the fungus gnats, you can clean up plant debris periodically.

Plant debris from decayed roots, stems, flowers, buds, or leaves can turn into organic matter. And guess what? It is favorable for fungus gnats, especially if you let the soil damp!

You can also bother your plants when you notice a fungus gnats infestation. That way, it will be easy for you to clean up the mess and start all over again.

We usually brush our pots and soak them in a bleach solution with water (1:9) for 10 minutes before washing them off with soapy water. It is beneficial to disinfect the containers, making them ready to grow healthy plants again.

Natural Remedies to Get Rid of Fungus Gnats

While chemical treatments like hydrogen peroxide spray can help eliminate fungus gnats instantly, some people prefer natural ways to get rid of those culprits.

Neem oil is one of the best natural remedies popularly used by many home gardeners.

Neem oil is way more effective than hydrogen peroxide as it can kill both adults and larvae of fungus gnats, thus breaking up their life cycle and boosting their removal from your houseplants.

However, using neem oil directly on the soil is not recommended as it can cause leaf burn. Instead, soil drenching with neem soil is one that can help you solve the fungus gnats issues.

This best home remedy is called systemic insecticides.

Natural Remedies To Get Rid of Fungus Gnats
Natural Remedies to Get Rid of Fungus Gnats

All you need to do is to prepare one quart of water into a bowl, then add a tablespoon each of neem oil and liquid dish soap.

Now, stir them with a spoon. After that, take 2 or 3 cups of the prepared neem oil for soil drenching, and dispense them at the base of the plants. Do this once or twice per two weeks.

Apart from soil drenching, you can use neem oil with rosemary to create a spray that can remove adult fungus gnats. Mix each tablespoon of neem and rosemary oil with one quart of lukewarm water. Then, transfer it into a mister.

You can spray it into infested spots on the soil without harming your plants.

If you have insecticidal soap, use around one tablespoon with ½ tablespoon of neem oil and blend it with one quart of lukewarm water. Next, transfer the mixture to the spray bottle and use it on any part of the plants where the gnats inhabit.

Chemical Products Solution to Get Rid of Fungus Gnats 

In addition to natural home remedies we have mentioned as the fungus gnats repellent, we also recommend several chemical treatments to eliminate fungus gnats from your indoor garden for good.

Luckily, they are widely available in the market and e-commerce, so you can grab them anytime.

1. Insecticidal Soaps and Oils

Insecticidal Soaps and Oils
Insecticidal Soaps and Oils

Not only gnats, but you can also use them to get rid of bugs and other plant pests that may be an issue in your garden.

Since the Garden Safe is already packaged as a spray, you must remove the sprayer and take one tablespoon to mix the same amount with the neem oil in a container. Add lukewarm water and find another empty sprayer to fill with the mixture. Now, you can use it!

We have shared a recipe to mix insecticidal soap with neem oil above. Now, we would love to share one of our favorite products to kill fungus gnats all at once, the Garden Safe Insecticidal Soap and Verdana Cold Pressed Neem Oil!

They are a perfect combo if you have infested gnats in your houseplants and must get rid of them immediately.

2. Botanical Insecticides

Botanical Insecticides
Botanical Insecticides

Botanical insecticides are types of insecticides made from botanical aliases of plants. One of the best is nothing other than pressed neem oil!

You can mix neem oil with various insecticidal soaps, essential oils (like rosemary or lavender), and hydrogen peroxide to kill fungus gnats (see the recipes in the previous section!).

Besides Verdana, we have another flagship neem oil product, the Harris Cold Press Neem Oil! Apart from treating the gnats, you can use it in your organic garden to keep your crops healthy.

In addition, it makes the best blend for your shampoo! Just add it with your favorite shampoo product to have healthy hair.

3. Systemic Insecticides

Systemic Insecticides
Systemic Insecticides

As its name bears, systemic insecticides combine two methods that work continuously to solve one issue. Nonetheless, it is not widely available in many countries as some have banned it because its use can kill non-targeted beneficial insects.

One that we recommend is Systemic Houseplant Insect Control from Bonide.

To apply it, add it to the soil and water it. This will kill the gnats and provide 8 weeks of protection against other pests, like aphids and whiteflies!

4. Chemical Soil Treatments

Chemical Soil Treatments
Chemical Soil Treatments

The most popular chemical method to get rid of fungus gnats is to use hydrogen peroxide. However, you cannot pour it directly into the potting soil. Instead, blend it with water, so the concentration is not too high.

Generally, we use a 1:6 ratio for hydrogen peroxide and water. 

After that, drench the soil with the mixture for 30 seconds. It will kill the gnats while ensuring your plants thrive, as this chemical will break into water and oxygen. We recommend purchasing Swan Hydrogen Peroxide!

You can use the mixture in spray bottle or add one cup to the soil directly.

Tips and Recommendations to Get Rid of Fungus Gnats

Now that you know the various methods for removing these insects, we have some recommendations you can use to get rid of fungus gnats for good in houseplants.

Instead of chemicals, you can choose biological controls like introducing microbial fungicides, like beneficial nematodes and Bacteria Thuringiensis (BT).

Nematodes (Steinernema Feltiae) are microscopic roundworms that are natural enemies of the fungus gnats.

They attack the openings of the larvae, including the mouth and anus, to enter and reproduce within the larvae until it dies. After that, the nematodes will keep looking for the larvae until none are left.

Adult Dark-winged Fungus Gnat
Adult Dark-winged Fungus Gnat

Apart from this scheme, they release bacteria from Photorhabdus species to kill the larvae in just 24-48 hours. These parasites detect the presence of larvae using movement, carbon dioxide, and vibration.

In addition to nematodes, you can also use Mosquito Bits, which contain BT.

Using soil drenching, BT will be absorbed into the soil and coat the roots. In this spot, they will release toxins lethal to gnats larvae. In just 24 hours, these larvae will die, and their life cycle will break.

No more infestation, no plant quarantine!

However, the BT method is rather expensive. Some home gardeners prefer growing fungi repellent plants to repel fungus gnats. Some fungi repellent plants we recommend include lavender, chamomile, lemon thyme, chrysanthemum, and citronella grass.

They have a pungent scent; those gnats will be distracted from approaching. If you want to grow one indoors, choose the venus flytrap. This insect-eating plant will trap and eat the gnats within their modified leaves.

Final Thought

If you want to know how to get rid of fungus gnats in houseplants for good, you must understand what factors cause these culprit infestations. The three most important factors are humidity, organic matter, and temperature.

Therefore, you must pay attention to the drainage from your plant pots so the soil doesn’t get wet.

In addition, ensure proper air circulation and good lighting from the sunlight so that air humidity can be maintained properly. In case you notice gnats flying around your potted plants, immediately set aside your plants from the rest.

Instead of using chemicals, we highly recommend the natural method with neem oil. You can also mix it with insecticidal soap and essential oil to repel the pest.

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FAQs (Frequently Asked Questions)

Are fungus gnats a problem year-round?

As these insects have overlapping life cycles, they can be a pest problem all year round. This is exacerbated because of its rapid reproduction in a short time. One generation only takes 4 weeks!

Hence, you have to set a pest control strategy to get rid of it, whether it’s using companion planting, hydrogen perixode, or microbial fungicides, you can try each to find the best one for your indoor gardening.

Why do I have so many fungus gnats?

If you have infected houseplants with fungus gnats, you must be aware of high humidity in your home.

Whether it is caused by leak pipes or overwatered houseplants, such a condition will promote fungi growth and thus inviting these insects to reproduce and spread. Wet soil is favorable for gnats to lay on their eggs and larvae.

Can plants survive fungus gnats?

Contrary to other pests, adult fungus gnats are actually not the main problem that can ruin your organic garden. They are only a nuisance. Nonetheless, the fungus gnats larvae are the predators of your infected organic garden.

These culprits grow and spread fast and thus their presence can damage your plant’s roots.

They can even make these plants grow stunts, especially young plants as they mostly grow delicate parts. Hence, you better kill the gnats larvae once you notice them in your garden.

Will fungus gnats go away on their own?

Unfortunately, the fungus gnats will not go away by themselves. You must find a way to kill the fungus gnats infestation. The only way to solve the fungus gnats problem is to apply pest control.

If you want to get rid of fungus gnats, larvae, eggs, and the adult ones instantly, we highly recommend using hydrogen peroxide solution. Blend 9% hydrogen peroxide with water in a 1:6 ratio.

How long do fungus gnats last?

The eggs will hatch into fungus gnats larvae in three days.

Fungus gnats larvae generally live and feed for 14 days before turning into pupate. During this stage the fungus gnats pupate will last around 3-7 days on the soil surface. Once the pupate transforms into adult fungus gnats, they will live approximately 8 days.

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