Isn’t It Aggravating When You Find Fungus Gnats On Your Houseplants? Here’s An Ultimate Guide To Get Rid Of It! (2021)

Adult fungus gnats on houseplant

Pests like the dreaded fungus gnat and its young, the fungus gnat larvae, are a major nuisance in most indoor gardens.

The little critters can wreak havoc on your plants if you don’t take care of them – and they can do it quickly.

As plant lovers, we hope that pests do not cause damage to our beloved plants.

But we are especially wary of pests on houseplants, because this brings the problem inside our homes.

However, fear not! You will learn how to defeat fungus gnats in your houseplants with 4 easy and non-toxic methods…

…plus how to avoid them altogether in the first place!

Fungus gnats on houseplant

Let us hear Sheilla’s story!

Meet Sheilla, a week ago she noticed lots of tiny flies hovering around the surface of the soil...

…she noticed even more yesterday and is quite sure they are fungus gnats

At first she don’t know what to do… 

She said that she was so discouraged that she could cry as the fungus gnats damaged her lovely Geranium…

but, as soon as Sheilla learned these five natural ways for getting rid of fungus gnats, She could not stop smiling!. 

Here is the main thing…

5 Natural ways to Get Rid of Fungus Gnats:

  • Create an inhospitable environment
  • Use a Soap-and-Water Mixture
  • Use Sand or Gravel
  • Dispose of the Top Layer of Soil Outdoors
  • Use Biological Control Methods

Let’s take a look at each option! However, before that…

What are fungus gnats?

“Fungus gnats are small flies that infest soil, potting mix, other container media, and other sources of organic decomposition. Their larvae primarily feed on fungi and organic matter in soil, but also chew roots and can be a problem in greenhouses, nurseries, potted plants and interior plantscapes. Adult fungus gnats may emerge from houseplants indoors and become a nuisance.”

Statewide Integrated Pest Management Program of University of California Agriculture & Natural Resources
Fungus gnats on houseplant
Credit :

You were probably wondering…

How to identify gnats in houseplants?

An easy way to tell if you are about to run into a gnat problem is to look for eggs.

The eggs of fungus gnats are laid in the soil and the larvae feed on  fungi in the soil of plants.

The larvae of fungus gnats measure about 1/4-inch in length with a shiny black head…

…and a elongated, whitish to transparent body.

Keep Reading…

Aside from fungi, they also like organic matter, which means that sometimes…

…they will eat the roots or seedlings of plants resulting in the plants appearing wilted.

See if you can find a slime trail similar to what slugs and snails leave behind. When you see a trail…

…your indoor plants may have gnats in them.

Fungus on housplant

Generally, gnats are attracted to light so you may notice them on your windows…

…especially if you have houseplants nearby. 

On the other hand..

Many people confuse gnats with fruit flies, but the two insects are  completely different.

In contrast to fungus gnats fruit flies are tan and look like miniature houseflies. They feed mostly on fruits.

Natural Ways to Get Rid of Fungus Gnats

Let’s jump right in!

The good news is that you don’t have to bomb your house with pesticides to keep soil gnats away.

Get rid of gnats from your soil naturally by treating your houseplants with these methods.

Create an inhospitable environment 

Consequently, the larvae of fungus gnats must be dried out because they thrive in moist  soil.

When you let the soil completely dry before your next watering, the gnats will be destroyed in the soil…

…and new adults will not lay eggs.

Use a Soap-and-Water Mixture

Pour a cup of water into a glass and add a few drops of liquid dish soap or Castille  soap.

This can be sprayed on the soil surface to kill larvae. Make sure all of the larvae have been killed…

…by repeating this process in a few days.

Use Sand or Gravel

It is only the top inch of the soil where fungus gnats lay their eggs. In addition to creating a dry environment…

…replacing the top inch with sand or gravel robs them of nutrient-rich fungi.

They would not want to lay eggs if their food source wasn’t available.

Dispose of the Top Layer of Soil Outdoors

It is still possible for the eggs to hatch. Instead of letting them hatch inside, let them hatch outside.

It isn’t a good idea to just move pests from one room to another.

Use Biological Control Methods

Fungus gnats can be controlled biologically, but they are mostly used in greenhouses where plants are propagated. 

I’m not going to lie to you…

You’re better off giving up your houseplants and starting over…

…if gnats have gotten out of control and are causing a pest problem with your houseplants.

Credit: Julie Martens Forney

If you would like to use botanical controls, your best option is Bacillus thuringiensis subspecies israelensis (Bti)…

…which is a bacteria that is used to control mosquitoes in ponds.

In addition to controlling gnats, these bacteria are also safe to use on humans and animals.

If you find a mosquito dunk or granules (in the home or garden center near the pond supplies)…

…in the pest control section, then you’re looking for “Bt.”

It is likely that you will need more than one application but follow the label instructions.

Mosquito dunks are dissolved in water and used to water plants.

As each watering is done, the soil is sprinkled with granules which introduce bacteria to the soil.

The steps mentioned above will help you eliminate fungus gnat infestations naturally.

How to Prevent Fungus Gnats?

Let’s talk about the steps you can take to prevent any pests from  entering your life in the first place!

Keep Your Houseplant from Becoming Overwatered

Because fungus gnats cannot survive in dry soil, you should let your soil dry completely…

…between waterings as often as possible.

Water from the Bottom

This will keep the topsoil (where the gnats lay their eggs) dry, as well as retaining moisture for your plants.

Put Extra Potting Soil in an Airtight Container

Fungus gnats can easily lay eggs in your potting soil if you keep it in the bag it came in.

To prevent gnat larvae from spreading, keep airtight containers with tight-fitting lids like buckets.

Sum Up

That’s quite a list. In summary, here are some of the best tips to save your houseplants from fungus gnats:

  • Create an inhospitable environment for fungus gnats
  • Use Soap and Water Mixture to kill the larvae
  • Use sand or gravel to creating the dry environment so that they won’t lay the eggs
  • Dispose of the top layer of soil outdoors to  let them hatch outside
  • Use biological control method by using Bacillus thuringiensis subspecies israelensis (Bti)…
    …a bacteria that is used for  mosquito control in ponds.

The fungus gnats population is usually higher during autumn.

It’s possible that they hitchhike on plants when they’re brought inside after the summer.

Make sure your plants are free of insects before bringing them indoors. 

Before you purchase new plants, you should examine them to make sure there are no insect infestations…

…and when planting or repotting, use a sterile potting mix.


Fungus gnats are more of an annoyance than anything else in small numbers. Gnats are not actively harmful to plants…

…or people as adult insects are. In large populations, larvae can feed on the roots of plants, causing significant damage.

Getting rid of fungus gnats is all about consistency you need to make sure that you try the methods regularly.

I hope this post show you how to get rid of fungus gnats in your houseplants. Now I’d like to know…

…what you have to say which technique from this post are you ready to try first?

Either way let me know in the comment section below!

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