Houseplants Plant pests

Earthworms in Your Houseplants?

Question

I found some small earthworms in the soil of one of my houseplants. I think they’re affecting the growth of the plant: it seems to be declining. What should I do to get rid of them?

Paul T.

Answer

Earthworms are not very common in houseplants, largely because the conditions in our homes aren’t much to their liking. Certainly, they can’t reproduce there and, moreover, remain small. Plus, there is often only one or two in the pot, not dozens.

You may occasionally find small earthworms in your houseplants. Photo: www.growweedeasy.com

Inevitably, you’ll find earthworms only in plants that spent the previous summer outdoors. The worms moved into the potting soil while the plant was outside and remained prisoners when it was brought back indoors in the fall.

Most home gardeners don’t even notice their plants have worms unless they repot and find worms burrowed in the soil, but sometimes you discover their castings (little heaps of poo) under the pot, near the drainage holes, or see the worms themselves when they rise to the surface after a particularly abundant watering. 

You’ll likely only find earthworms in the soil of plants that prefer moist conditions; worms just don’t thrive in soil that dries out completely between waterings.

Normally, earthworms aren’t harmful to plants. On the contrary, they’re beneficial, aerating the soil through their tunnels and enriching it with their castings. But in pots, their main food, the organic matter normally present in soil, isn’t very abundant, especially since most potting soils are largely composed of peat or coir (coco fiber), two materials slow to decompose and mineral-poor offering almost nothing that an earthworm can consume. Under those circumstances, the worms begin to eat the young roots of the plant growing in the pot and that can, of course, hinder its growth, even possibly kill it.

What to Do?

Let’s start with prevention.

Soak the pot in soapy water to chase earthworms out. Ill.: Claire Tourigny & www.clipartmax.com

Before bringing your houseplants back indoors in the fall, plunge their pots into a bucket of soapy water and keep them entirely emerged for about 20 minutes or so. Earthworms dislike both water and soap and will rise to the surface, trying to escape. You can then pick them up and put them back in the garden. This will also rid the potting mix of most other soil pests.

If you skipped the first step (soaking the plant before bringing it in), you can also eliminate any worms by letting the potting soil completely dry before watering again. That’s why you rarely find earthworms in pots of succulents and other plants that are allowed to dry out deeply on a regular basis.

If you find them in houseplants that won’t tolerate their soil drying out completely, just repeat the same treatment you should have used in the fall before bringing the plant in: give the entire rootball a 20-minute soak in soapy water, then remove any worms that show up.

In winter, however, you won’t always be able save the worms you find. After all, you can’t successfully release them outdoors if the ground is frozen. Instead, try putting them in your compost bin: it may be just warm enough to keep them alive. Otherwise… well, let’s just say that dead earthworms are an excellent composting material!

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, laidbackgardener.blog will continue its mission of demystifying gardening and making it more accessible to all.

17 comments on “Earthworms in Your Houseplants?

  1. Aileen Thorne

    Could you not spray the soapy water into the roots!

  2. Doesn’t the soap kill the worms? I don’t want to kill them. Can I flush them out with water alone?

    • Yes, but will you be able to save them? If the ground is frozen outdoors, you won’t be able to “set them free”.

      • I discover only one earthworm in jasmine planter from cuttings. Since the ground is frozen outside and it’s benefiting my vine I’m going to wait until the ground has warmed up and thawed to release it in April. There’s no harm in doing so, favour for a favour is the way I look at it. It did the peekaboo with me when I watered the plant.

  3. Could you please indicate how much soap per water ratios? Also what kind of soap?
    Thanks

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  5. Lucinda Farnworth

    I couldn’t figure out why my starts kept dying.
    Till I found all this fat healthy worms in my house plants pots. I JUST changed all my pot to new potting soil .WISH ME LUCK

  6. I had a small Holy Basil sapling that was growing well till I added a tablespoon of vermicompost to it. Weeks later I found the plant droopy n shedding leaves. Finally the weakened stem bent. When I lifted the pot an earthworm wriggled out of the drainage hole. Days later when I emptied the pot I found adult as well as baby wrigglers in the moist soil. I guess they damaged the roots.

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  10. Thanks for the tip on soaking pots in soapy water. i always bring a few “pets” in with my herb pots in fall and this might solve that problem!

  11. Did you actually see a picture of Paul’s worms? I hope they were actually earthworms and not some kind of root weevil or maggot.

    • No, and I cut back considerably on the question. When I wrote him back about it, because I was convinced it was something else, he claimed he knew what earthworms were and that was definitely what he had. I’ve brought in a few over the years, but never paid too much attention to them.

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