5 Brilliant Ways to Get Rid of Houseplant Pests, According to a Plant Expert

published Jun 22, 2022
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Fungus gnats — you might not know them by name, but if you’ve got houseplants, you’ve likely come across them. These small flying pests are often mistaken for similarly sized fruit flies. You may find them crawling on the soil at the base of your plant, or worse, they may erupt like a cloud when you brush against your greenery’s foliage.

Although harmless in the sense that they won’t bite or spread disease, these gnats are definitely a nuisance and, well, kind of gross. They also reproduce like crazy and their larvae can feed on thin roots, causing damage to your beautiful houseplants. “They’re one of the most common houseplant pests,” says Danae Horst, founder of Los Angeles-based plant shop Folia Collective and author of Houseplants for All. “People coming into my shop ask about them constantly.”

The good news? Fungus gnats can be easily managed and you (and your potted friends!) can be rid of them. Here are Horst’s five tips for preventing and fighting fungus gnats.

Credit: Diana Paulson

1. Ensure good drainage.

If you’ve got a struggling houseplant, there’s a good chance poor drainage is to blame. Soggy soil and stagnant water at the bottom of a pot can create many issues for your plants. To top it all off, those conditions are a prime breeding ground for fungus gnats. So the first step in the battle against these pesky pests is a simple one: “Choose containers with drainage holes when potting your plants,” says Horst.

If you simply can’t resist a beautiful fully-sealed container or you’re nervous about creating your own drainage holes, try the cachepot method. “Keep the plant in a plastic nursery pot which has plenty of drainage holes,” explains Horst, “and place it inside a decorative container. When it’s time to water, just remove the plant in its plastic pot, give it a drink, allow excess water to drain out, and then return the plastic pot to the decorative outer container.”

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2. Let your soil dry out between waterings.

Even with good drainage, overwatering can be a problem. Excessive moisture can attract adult fungus gnats and create a cozy place to lay eggs, so be sure to let your plants dry out between waterings. This doesn’t, however, mean that you should use less water when giving your plants a drink. “For the health of the plant,” says Horst, “it’s best to fully saturate the whole root ball each time you water — you’ll just be doing it less frequently.”

Credit: Joe Lingeman/Apartment Therapy

3. Remove standing water.

This tip is a simple one, but can be easy to forget. Fungus gnats also love pools of water that accumulate in saucers beneath pots and at the bottom of cachepots, so be sure to frequently dump out inviting puddles. If you have heavy pots that are too difficult to move, Horst has a clever hack: use a baster to suck up the excess water or sop it up with an old towel.

Credit: Viv Yapp

4. Swap out your soil.

If you’ve done all of the above and still have fungus gnats creeping around your plant, it’s likely time to swap out your soil completely. “Sometimes plants come in a potting mix that is too dense and doesn’t drain well,” says Horst. “Or worse yet, you may have brought a new plant into your home with a potting mix that already had fungus gnats breeding in it.” Yuck! Horst recommends repotting your plant with soil that includes chunks of bark or coco coir and some pumice or perlite — all of which help with drainage. “A chunky potting mix will dry out faster than a dense mix,” she says, “which will make it less appealing to fungus gnats.”

5. Wipe out an infestation with a proactive approach.

All the above tips are effective for preventing fungus gnats from taking root in your home or catching a problem in its early stages. But if you’ve got a full-on infestation, you’ll need to be more proactive. “Fungus gnats have a multistage lifecycle,” says Horst, “so once they’ve taken hold in your plants, you need to kill both the adults and the larvae to wipe them out completely.”

She suggests taking a two-pronged approach: First, place sticky traps in each pot to catch the adults. Second, use a product such as Mosquito Bits (don’t be fooled by the name — it also does the trick for fungus gnats) into the soil to battle larvae.

How do you deal with pesky houseplant pests? Tell us your tips in the comments below.