Home Plant Pests How to get rid of fungus gnats in houseplants

How to get rid of fungus gnats in houseplants – GIY Plants

Potted plant with yellow gnat traps full of gnats

There are several ways to get rid of fungus gnats in houseplants. The best method is to keep the soil surface dry since eggs are only laid on wet soil. Let the top 1 inch of soil dry between waterings and/or add a 1 inch layer of coarse sand on top. The sand will dry out quicker than the soil.

Fungus gnats take about 4 weeks to grow from egg to adult. The University of Wisconsin suggests continuing any control method you use for at least 4 weeks to get rid of fungus gnats.

Fungus gnats are typically more of a nuisance and won’t kill your plant. However, larvae can feed on small roots near the soil surface. If populations become too large, root feeding may lead to plant stress and root disease.

How To Get Rid Of Fungus Gnats In Indoor Plants

There is a lot of misinformation about getting rid of fungus gnats online. Contrary to popular belief, the University of Wisconsin says that fungus gnats are not attracted to vinegar or water traps like fruit flies.

North Dakota State University also states that there is no research to support claims that pouring hydrogen peroxide or vinegar on your soil kills fungus gnats. They note that it may also harm your plants.

Below are the top university research based solutions to get rid of fungus gnats in indoor plants.

Remove Dead Plant Debris

Fungus gnat larvae feed on dead plant material. Removing dead plant debris from the soil surface will limit their survival.

Cover Drainage Holes With Cloth

Fungus gnats may find their way into the drainage holes at the bottom of the planter and lay eggs. This can happen when populations become very large or you add a layer of sand to the top of the soil.

Cover the drainage holes with cloth and secure it with a rubber band. This will allow water to pass through but prevent fungus gnats from getting to the soil.

Water Plants From The Bottom

Water your plant from the bottom by adding water to a saucer and letting the soil suck it up. This will keep the top of the soil dry and stop gnats from laying eggs.

Sticky Traps

Place sticky traps around your plants to catch gnats. Use yellow and white as those are most attractive to gnats.

Bacillus Thuringiensis (Bt)

Bt is a bacteria that occurs naturally in the soil and kills larvae of flies and moths. Wrap a mosquito dunk, which contains Bt, in a piece of thin cloth and secure it with a rubber band. Place it in your watering can with water overnight. Remove the mosquito dunk and water your plants normally.

Repeat this process every time you water your plants for several weeks and the gnats will disappear.

Frequently Asked Questions

What home remedy kills gnats in houseplants?

Most home remedies for killing gnats are not supported by research. The best protection you can provide is to put a 1 inch layer of coarse sand over the soil so it will dry out faster and reduce egg laying. Also cover drainage holes with cloth to keep fungus gnats from laying eggs.

Will vinegar spray kill gnats?

Vinegar is not toxic to gnats. The only way vinegar spray may kill adults is if they become stuck in a droplet and drown. Bacillus thuringiensis is the best option for killing gnat larvae in the soil and eliminating fungus gnats for good.

How does white vinegar kill gnats in houseplants?

Vinegar is not toxic to gnats and doesn’t kill them. It can also harm your plants. Vinegar is typically used as an attractant in traps for fruit flies but doesn’t work for gnats. A better option is to use Bacillus thuringiensis to kill gnats in houseplants.

Why does my indoor plant have gnats?

There are two ways fungus gnats typically get into indoor plants. If you put your plants outside during warm weather, they can become infested. If you repot your plant, the new soil may be infested with fungus gnats. Fungus gnats are common outdoor insects and can also enter your home through open doors and windows.

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