A worm presence in a large garden can be beneficial to plants, the worm casings providing nutrients and their wriggling bodies aerating the soil. In a single houseplant, however, worms can lead to a decline in plant health because they nibble on plant roots – especially if there is no decaying plant matter available in the soil. The common earthworm, cutworms and composting worms such as red wigglers are most likely to be found in houseplants, but several pests have worm-like larval stages that can be treated in the same way as a real worm infestation.
Inspect each plant carefully for signs of worm infestation. In some cases, the worms might be present on leaves or on the soil surface. Earthworms tend to burrow in the soil at the bottom of the pot so you might be able to find them with a little digging or by peeking through the pot's drainage holes. Earthworms tend to reveal themselves more readily at dusk and on cloudy days, but shouldn't be too difficult to spot within the confines of a planter.
Move worm-infested houseplants to a quarantine room away from any other houseplants so the problem doesn't spread to unaffected plants. Keep them separated for a few weeks, which allows time to get rid of the worms and to check that the problem doesn't persist before moving them back in the original location. Any new houseplants you bring into your home should be treated this way to avoid the spread of worms and other pests, as well as diseases.
Pick off any worms that you can see on the soil surface and on plant leaves. You should be able to pick up surface worms between your fingertips, but a pair of tweezers works well if you prefer not to touch the worms. This might be all you need to do to get rid of worms unless you have earthworms in the soil.
Release earthworms or composting worms outdoors in a vegetable garden or flower bed where they are beneficial to the soil, but far away from other potted plants. Harmful pests such as cutworms and leafminer larvae should be submerged in warm, soapy water to kill them so they don't harm other plants. There are a range of insecticidal soaps that are effective at killing pests. Use a ready-to-use insecticidal soap and spray the worms, repeating the application as needed.
Submerge the houseplant pot in a bucket or tub filled with cool water – the container must be wider and deeper than the planter. Pull the pot out of the water immediately after completely saturating the soil. Like a beating rain on the hard ground at dusk, this practice often drives earthworms out of the soil so you can catch them and release them outside. Additional action might be needed if this doesn't get rid of the worms.
Repot the houseplant in clean, sterile potting soil. Remove the plant from its original pot and shake excess soil loose from the rootball so you can access and pick off any worms in the soil. You can repot the plant in its original container after thoroughly washing the container in a 10 percent solution of diluted bleach. If it appears rootbound, move it up to a slightly larger pot.