How to Get Rid of Fungus Gnats Forever in Soil and Houseplants

Here are the tried and tested methods for getting rid of fungus gnats in your home permanently. These minor household pests can become a major nuisance if the infestation gets out of hand. Act quickly before the fungus gnats engulf your home.

Common Sources of Fungus Gnats

The first and most important step of pest control is prevention and to understand the source of the problem. There are several things that may attract the fungus gnats.

For starters, most if not all fungus gnats you come across originate from the houseplant soil. They will grow in numbers if the houseplant soil has too moisture or if there is a lot of decaying matter (e.g. dead leaves) in the potted soil.

In most cases, fungus gnats will disappear on their own if you get rid of the excess moisture and decaying matter in the houseplant soil. If the flies aren’t originating from the houseplant soil then you may be dealing with a different type of house fly. In such cases, we suggest trying these additional gnat control methods to deal with the infestation.

Methods to Get Rid of Fungus Gnats

If there is already an active infestation at hand, you may not want to wait around for the gnats to disappear on their own. Here are the remedies we suggest to get rid of these tiny flies forever.

Place Yellow Sticky Traps

Grab a pack of yellow sticky trap and place them in the vicinity of the infested houseplants. This is a great home remedy for those who want to stick to eco-friendly, non-pesticide methods.

Decaying Fruit and Vinegar Trap

Fungus gnats like decaying matter and you can use that to your advantage to lure the flies to their doom. A simple homemade vinegar trap for fungus gnats consists of a plastic cup, white or apple cider vinegar, saran wrap, and dish soap.

You just need to pour some vinegar into the plastic cup, mix in a few drops of dish soap, then wrap the cup with saran wrap and poke a few holes through for the gnats to enter. Once ready, place the cup in the vicinity of the infested plants.

Methods to Get Rid of Fungus Gnat Larvae

The above methods will only eliminate the adult flies. The fungus gnat lifecycle will continue and re-populate if you don’t deal with the larvae and eggs as well.

Apply Mosquito Dunk to the Soil

The most effective way to get rid of fungus gnat larvae is by applying mosquito dunks to the soil. Mosquito Dunks is a biological control method that get rids of the larvae with the help of a bacteria called Bti. Let the mosquito dunks sit in a bucket of water until it dissolves, then pour an appropriate amount of treated water into the infested houseplant soil.

Pour a Light Layer of Sand

Some people have had success controlling fungus gnat infestations by adding a light layer of sand on top of the soil. This may discourage the eggs from hatching and may also help dry out the soil.

Drench the Diluted Hydrogen Peroxide

Another effective method to get rid of the fungus gnat larvae is to drench the soil with diluted hydrogen peroxide. Mix one part 3% hydrogen peroxide with four parts water. Apply the hydrogen peroxide solution once the soil is almost dry. You might see a bit of fizz after application. This is perfectly normal and nothing to be concerned about.

Replace the Houseplant Soil

In the worst case scenario, you may need to replace the houseplant soil if the infestation is beyond control. Make sure to only use high-quality potting mix that’s unlikely to contain any gnat larvae or eggs.

Methods that Are Unlikely to Work

Don’t waste your time on the following remedies for killing fungus gnats. These methods are unlikely to be effective at getting rid of the tiny black flies.

Sprinkling Cinnamon Powder on Soil

Cinnamon powder is considered a natural fungicide but it’s a hit-or-miss method. It may potentially lessen the fungus gnat infestation but it won’t wipe it away completely.

Adding Coffee Ground to Soil

Used coffee ground is also purported to help control fungus gnats but it’s unlikely to be an effective remedy. You would also be making the situation worse if you add wet coffee ground to the soil (even more organic matter for the gnats to feed off from).