Worm casts in your lawn

Worms are a vital part of your lawn’s ecosystem. Earthworms act as nature's aerators, moving through your soil and digesting lawn thatch whilst feeding air through to the grass root system. In extreme cases, worm castings can damage grass and help new weeds to take root in your lawn.

What is a worm cast?

As an earthworm moves through your lawn and eats its way through dead plant debris, the earth that it eats is expelled through its digestive tract. Most of the time this happens below the surface of the lawn, but on occasion it will appear as a small coil of fine earth on the surface of the lawn.

How worm casts can harm your lawn

The soil that a normal worm excretes is perfectly harmless to plants and animals — there’s nothing poisonous in it — but it can ruin the even green appearance of your lawn. Worm casts are most likely to appear in mild damp weather, particularly in spring and autumn. These little brown buttons of untouched soil are popular germination launchpads for weeds and moss, so it’s best to try and stay on top of them.

If you're getting a lot of worm castings but your lawn is still suffering from poor aeration, then it's likely you've got too many casting worms in your lawn. A casting worm is a specific type of earthworm (the Aporrectodea and Lumbricus species) that is very good at producing worm castings, but not particularly good at aerating the soil.

Worm cast control

Earthworms like soils within a certain pH range, so one of the methods we use to reduce the likelihood of worm castings is to change the pH balance in the soil. We start by checking the pH levels, then gently increasing the acidity where appropriate. Our goal is never to remove worms completely from your lawn, but to keep the worm population in harmony with the natural needs of your garden.

Get a free lawn analysis

If worm castings are becoming an eyesore in your lawn or prompting new weed growth, give us a call. We’ll take soil samples and come up with a treatment plan built around the unique needs of your lawn.


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