7 SIMPLE Ways to Reduce Fungus Gnats Indoors

2 comments by Luke Marion

Fungus gnats are ANNOYING! 

Fungus gnats are the bane of any gardener or houseplant enthusiast. Those pesky little bugs fly around your plants, fly around your face, up your nose, in your eyes, and worst of all they eat plant roots and cause damage to plants! 

So how can you correct the problem, or stop it from ever happening in the first place? In this article, I will give you 5 easy tips for preventing and even controlling them entirely. 

CRITICAL MISTAKE: Only trying to kill the adults. Yes, the adults are part of the problem, but the eggs and larvae are the real problem. Target the adults with sticky traps, and then focus your energy on the soil! Because that's where the problem lies.  

What a Fungus Gnat needs:

moisture: Fungus gnats need damp conditions. Their larva require adiquate moisture to grow, and develop into flies. The adults only live 24-48 hours and most of the damage is caused below the soil. 

Organic material: As the name implies, a fungus gnat relies on… fungus to call a food source. Not just fungus, but also roots, living or dead, compost, organic matter, or anything that can be consumed for food. 

holding compost

remove organic material: compost and many bagged soils contain compost. This organic material will often host fungus gnat larva, which live and breed in the compost. By going with a soil-less mix, it may cost a bit more, but often it doesn't contain as many unwanted hitchhikers. 

holding compost

reduce watering:  Watering your plants is a chore, but often gardeners overwater their plants, leading to access water. This excess water can lead to many problems like root rot, damping off, but also fungus gnats. 

By letting your plants dry out in between waterings, it will greatly reduce the risk of hosting a community of unwanted fungus gnats.  

holding compost


Neem oil: Coming from the neem seed, this oil contains chemicals that are organic, but very useful at controlling the fungus gnats. Neem oil can also be used to control aphids, spider mites, and other pests! By mixing it in with water, and adding a few drops of dish soap allows you to water the soil and drench the soil. 

Pyrethrum: Pyrethrum is from the daisy family and actually prohibits the reproduction cycle of the fungus gnat. There are many different organic options that work, but they all work basically the same. 

courtesy: curious plant


Boiling water: Boiling water will kill fungus gnat larva when poured into bagged soil. Before planting, pour boiling water into the soil to sterilize the mix and rid it of any fungus gnats. 

Heat-treating soil: By placing your compost into the oven for 5 minutes at 350, your soil will be sterilized and free of any unwanted fungus, mildew, bacteria, and pests like fungus gnats. 

Natural Barriers

Sand: fungus gnats use a corkcrew-like egg depositing method to bury the seeds. An adult fungus gnat can lay anywhere from 300-500 eggs in a single life cycle! The most simple way to prevent the fungus gnat fro laying eggs is by applying sand to the surface of your seed starts and pots of soil. 

All it takes is a layer roughly ¼-½ " thick, we use playground sand, as it is the cheapest option. Almost any hardware store will have it.  


  • Richard DelPivo

    I had a really bad infestation of fungus gnats so I tried everything to get rid of them. Replacing the sand with diatomaceous earth and bottom watering helps. The most effective treatment that I found was the mosquito dunks that contains Bacillus thuringiensis israelensis. Everything else was only marginally effective for me.

  • Theresa C

    This is going to be a more rewarding experience thanks to this how to get rid of gnats information. Thanks! 😊

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