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How to Deal with Fungus Gnats on Houseplants



One of the most common questions we get asked about houseplants is how to get rid of fungus gnats! Let’s start with the basics. What are they? Fungus gnats are tiny little winged creatures that look like a little mosquito but are the size of a fruit fly. They’re easy to spot because you’ll see them flying around! They are in fact a type of houseplant pest but thankfully, they are less damaging than other types of pests, and easy to get rid of.

Tip #1: Let your soil dry out


A fungus gnat infestation usually starts because the soil is staying too moist. Gnats love moist soil and will only survive if it stays moist. They lay their eggs in the top layer of the soil. It’s important to adjust your watering schedule depending on the time of the year. Our homes are much warmer and more humid in the summer, which will require more watering, but drier and cooler during the winter, which means we typically must cut back on our watering during the winter months. We recommend using a moisture meter, to check when your plant needs some water. By letting your soil dry out in between each watering, you will help break the fungus gnat’s lifecycle. You can also take a pencil or chopstick, and move the top layer of soil around, to disrupt their eggs.

Tip #2: Use sticky cards


You’ve likely seen or heard of these before. Sticky traps are a great way to catch the adult fungus gnats and speed up the process. Place the yellow sticky cards just above the soil of your houseplants. The gnats will land on them and get eliminated! Be sure to replace your sticky cards once they become full of gnats. Remember, the more sticky cards you set up, the higher chance you’ll have of getting rid of them faster!

Tip #3: Getting rid of their eggs


Now that you’ve set yourself up to kill the fungus gnat adults, it’s time to kill the next generation! Fungus gnats lay eggs in the top layer of soil, to keep reproducing more. It’s very important to get rid of their eggs so that more don’t hatch! Here at Robert Plante Greenhouses, there are two very effective methods that we recommend:


1) Using beneficial nematodes: To control fungus gnat eggs, we can release beneficial nematodes in the soil. These are microscopic bugs that attack gnats at the larvae stage. Pick up a bottle of Nemaknights for Fungus Gnats on your next visit to the greenhouses.


2) Using Mosquito Dunks: Another alternative that is very effective at getting rid of the fungus gnat eggs are by using mosquito dunks! Mosquito dunks are round pucks that contain a beneficial bacteria that infects and kills the larvae of flying insects including mosquitos, fruit flies and fungus gnats. Fill a gallon jug or large watering can with water and allow the mosquito dunk to soak in the water overnight. Then, remove the dunk which you can re-use next time, and use that water when it’s time to water your houseplants. Remember, it’s important to keep using mosquito dunks every time you water until the gnat infestation is completely gone.


That’s all! Although fungus gnats are annoying, they can definitely be treated for pretty easily. Make sure to use the tips above for the best results! If you have any questions, don’t hesitate to contact us for more information.

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