How to get rid of fungus gnats in houseplants

Monstera: Houseplant expert details how to remove pests

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Fungus gnats, also known as houseplant flies or sciarid flies, cause minimal or no damage to house plants, but they can be a pest. These little black flies thrive off the algae, fungi and plant roots of indoor plants which is why they are associated with houseplants. Getting rid of these pests is surprisingly straightforward, so here are the top four methods to eliminate them from your home. 

First, you need to identify if the flies are fungus gnat flies.

They are small and black and tend to fly around houseplants settling on their leaves and living in house compost.

Brits often mistake these flies for fruit flies, but you can tell the difference as fungus gnats will stick to houseplants leaving your fruit bowl well alone.

How to get rid of fungus gnats

Watering less

One easy way to get rid of these flies is to water less.

These gnats need damp compost to survive as this is where their two main food sources, algae and fungi thrive.

If you let your compost dry out the gnats will soon leave, but be careful not to harm your plants in the process.

Use gravel mulch

If your houseplants need to be watered regularly letting your compost dry out may not be an option.

Using gravel mulch is another great way to get rid of these gnats.

Simply cover the surface of your plant’s compost with 1cm of this gravel.

Over time you will see the gnat population diminish, as they won’t be able to reproduce with the gravel present as it will prevent them from laying their eggs in the compost.

Hydrogen peroxide

Chances are you might have a bottle of hydrogen peroxide under your kitchen sink.

Hydrogen peroxide is normally used as a cleaning product and is a great solution as it won’t kill your plants but it will kill eggs, larvae and adult gnats.

To make the solution, mix one part hydrogen peroxide with four parts water.

You can then use an empty spray bottle to spray your plants, or for the best results soak all of the soil in it.

You may find the solution will fizz and foam when it reaches the soil, but don’t worry as this is normal.

Make sure you use typical three percent household hydrogen peroxide as anything stronger could harm your plants.


If you are still struggling with these gnats traditional sticky fly paper can be very effective.

Simply hang up these yellow sticky traps near your houseplants or if you don’t have a suitable place to hang them from, attach them to a pole such as a bamboo cane and insert it into the flower pot.

Fly paper may be an eyesore but it will quickly trap these gnats so you won’t have to put up with the flies or these unsightly traps for long.

Be sure to keep these traps near the soil level as these gnats rarely fly high.

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