Home remedies for fungus gnat infestations


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Fungus gnats can be devastating to a garden. Here are some of the best homemade remedies against the dreaded pest.

A close-up shot of a gnat
Adult fungus gnats can often be found buzzing around infested flower pots [Photo: D. Kucharski K. Kucharska/ Shutterstock.com]

In Europe alone, there are more than 600 known species of fungus gnats (Sciriadae). The small flies can infest ornamental plants and vegetables inside the house as well as outdoors, while the larvae often migrate in large numbers, forming processions up to 10m long. If you are struggling with fungus gnats in the house, household remedies might be worth a try.

How to recognise a fungus gnat infestation

Fungus gnats are between one and seven millimetres long. Their bodies are thin and dark. The larvae, too, are slender with a white-grey body and black head. If you spot small flies buzzing around your flower pot, especially when you move the pot or water the plants, you are likely looking at a fungus gnat infestation. If a plant is infested with fungus gnats, it can struggle to grow and may remain small. You may also spot the larvae in the potting soil, feeding on the roots of the plants. This can cause severe damage; the larvae can hollow out the stems of the infested plants.

Struggling with an infestation? Here are even more fungus gnat tips and tricks.

A close-up shot of gnat larvae
Gnat larvae are white in colour and have a black head capsule [Photo: Henrik Larsson/ Shutterstock.com]

How to prevent fungus gnats with sand

Sand is great at preventing a fungus gnat infestation. Simply apply a thin layer of fine sand over the potting soil and you are done! This method is effective because fungus gnats need the surface of the soil to be wet to lay their eggs. Quartz sand is particularly well-suited for this method.

Tip: It is important not to get the sand wet when watering your plants. Try using a saucer underneath the plant pot.

A cactus is potted in a terrarium filled with sand
A thin layer of sand will stop gnats from laying eggs [Photo: Vrchkovski N.Materials/ Shutterstock.com]

How to get rid of fungus gnats with coffee grind

Coffee grind is great at removing gnat infestations. Dry the grind thoroughly – this will prevent mould from forming – and spread it over the potting soil. A thin layer will keep the female gnats from laying their eggs. Additionally, the coffee can fertilise your plants. That’s right: you can use coffee grounds as fertiliser!

How to get rid of fungus gnats with baking powder

Not only are baking powder and baking soda cheap, you probably already have some in your cupboards. Sift some of the powder over the surface of the soil, moisten, and wait. Fungus gnat larvae will absorb this moist powder and die.

A sieve filled with baking powder
Baking soda is another great solution for getting rid of fungus gnats [Photo: Nungning20/ Shutterstock.com]

How to get rid of fungus gnats with tea tree oil

Many people use tea tree oil on the skin. However, it is also a great solution for a gnat infestation. Combine 20 drops of tea tree oil with a litre of water. Water the infested plants with this mix, and you should help remove any larvae in the soil. For the adults, use some adhesive traps around the plant.

How to get rid of fungus gnats with lavender oil

Lavender oil is not only calming, but a great natural remedy for fungus gnats. The application and effects of lavender oil are similar to tea tree oil. Mix 20 drops of lavender oil with one litre of water, water the infested plants and wait. If the oil does not mix well with the water, add a tablespoon of soapberry powder to the mix as an emulsifier.

A tincture is pictured next to a bundle of lavendar
Twenty drops of lavender oil are enough for one litre of water [Photo: almaje/ Shutterstock.com]

How to get rid of fungus gnats with neem oil

Neem oil is very effective against fungus gnats. It comes from a tropical tree that is used a lot to combat infestations. Mix 10ml of neem oil per litre of water and water the infested plants. Neem oil is neither harmful for humans nor pets, and has plenty of other uses!

How to get rid of fungus gnats with garlic

There are several ways of using garlic (Allium sativum) to fight fungus gnats. Garlic cloves contain the sulphurous substance allicin, which can kill fungus gnat larvae. Either cut off the tip of a garlic bulb and stick it into the potting soil, or peel and dice some cloves and spread them over the soil.

Garlic rests in a bowl of cloves
Garlic kills gnat larvae [Photo: OShuma/ Shutterstock.com]

How to get rid of fungus gnats with parsley

Parsley (Petroselinum crispum) is another great solution. Chop the leaves into small pieces and spread them evenly across the soil. Fungus gnats cannot stand some of the chemicals in parsley, and will avoid it at all costs.

How to get rid of fungus gnats with nutmeg

Ground nutmeg is pictured next to a bowl of nutmeg
Spread grated nutmeg into a flower pot by watering [Photo: pilipphoto/ Shutterstock.com]

The myristic acid found in nutmeg is fantastic at combating fungus gnat larvae. Simply scatter some nutmeg powder over your soil and water. The spice will penetrate the soil and voilà!

How to get rid of fungus gnats with matches

Matches are another great solution for fungus gnats. Burn some matches and stick them into the soil head-down. Match heads contain sulphur, which prevents adults gnats from settling on the soil and removes larvae already there.

How to get rid of fungus gnats with tights

It may look odd, but tights are a very effective method against fungus gnats. Pull the tights up from the bottom of the pot, over the sides and then tie a knot around the stem of the plant. Not only will this prevent gnats from settling on the soil and laying their eggs, but the insects won’t be able to leave the pot to mate. However, for this method to be effective, you need to leave the tights on the flower pot for at least six weeks.

If household remedies are not doing the trick, there are plenty of other ways of getting rid of fungus gnats.

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