How to Deal with Earthworm Castings on Your Lawn

earthworm in grass

If the piles of soil in your yard are roughly the size of a quarter, you might have struck mulch gold. These piles are earthworm castings (also known as worm pooh) and they have great benefits for your yard. But sometimes too many piles of worm waste can be too much of a good thing. 

Our guide will show you how to strike a balance between reaping the benefits of earthworms and dealing with earthworm castings on your lawn. 

What are worm castings?

close-up of earthworm castings in grass

As worms wiggle beneath your yard’s surface, they consume soil, microorganisms, and organic matter. The material passes through the worm’s digestive system and exits as waste, also known as worm castings. 

Worm castings look like small piles of soil and are roughly the size of a quarter. Don’t mistake these poles with mole piles, which look like little volcanoes in the yard. 

Worm castings peak in autumn, but they can pop up in the yard at any time of year. They’re also a common maintenance problem in golf courses. 

How to deal with earthworm castings

When earthworm castings are ruining your lawn’s curb appeal, the last thing you want to do is spray the yard with non-selective pesticides to get rid of the worms. Killing all the worms in your yard might control the castings, but it’s only going to create more problems for your lawn. Pesticides can also harm other beneficial insects. 

To keep the earthworm castings under control, here’s what you can do: 

Grab the rake

Clear your lawn of earthworm castings by raking or sweeping the soil piles when they’re dry. Collecting them while they’re wet won’t do any good, so don’t perform this task after a rain shower. 

Once you’ve raked or swept up the castings, toss them in your compost bin or garden soil. While you enjoy a clean yard, your plants will enjoy free fertilizer. 

Adjust your watering routine

Overwatering encourages worms to rise to the surface (which is where they’ll leave their castings). 

In other words, you don’t want your lawn’s surface to be consistently moist. That’s why it’s better to water your lawn less often and for long periods than to water too often and for short periods. Watering infrequently and for long periods also encourages a deeper root system and is healthier for your lawn. 

And don’t give your lawn more water than it needs–– most established lawns need only 1 to 1.5 inches of water per week. 

Raise the mowing height

If you want your lawn to reap the benefits of worm castings, but you don’t like the way they look, raise your mowing height. The taller grass will help cover the castings. 

Lower the earthworm population

Sometimes excessive worm castings are a sign of a high earthworm population. To lower the number of earthworms in your yard, consider making conditions less hospitable (but don’t exterminate them with a pesticide). Learn how to control earthworms in the section below. 

How to control earthworms

If your yard is overflowing with worm castings, there are some steps you can take to lower worm activity. Earthworms are beneficial to your lawn’s soil, so you don’t want to get rid of them all –– just enough to minimize the unsightly castings. 

Remove thatch 

Thatch is the layer of dead and living organic matter that accumulates between the soil surface and the grass blades. Earthworms love to munch on thatch, so you can encourage them to search elsewhere for food by getting rid of their snack.

Manually remove the earthworms 

After a heavy rainstorm, worms will often wiggle to the surface. Pick up the earthworms and toss them in your compost bin, sell them to a local garden center, or use them as fishing bait. 

Introduce a natural enemy

Birds will gladly keep your earthworm problem in check. Invite them to the yard with bird feeders and birdbaths. 

Chickens also can help control worms, but they’re not always a good option. Why? Because you’ll have to deal with chicken pooh on the lawn instead of worm pooh. 

Reduce organic matter 

Do you routinely add compost as a top dressing over your lawn? Minimizing the application of organic matter can help ward off earthworms. Removing grass clippings also will restrict organic material on the lawn. 

What are the disadvantages of worm castings?

Worm castings offer significant health benefits for the lawn’s soil, but worm castings have their drawbacks when they take over the yard. 

  • A yard with too many worm castings can look unkempt and ruined, feel lumpy and uneven. 
  • Worm castings can make lawn mowing difficult, and they can even dull the mower blades. 
  • Excessive castings in the yard also might signify that your soil has a high number of earthworms. This makes it an attractive hunting ground for moles, gophers, and armadillos, which can easily tear up your lawn. 

What are the benefits of worm castings?

Worm castings aren’t all bad. Many homeowners would be pleased to find some worm castings in their yard. 

Benefits of worm castings for the lawn

  • Increased soil fertility: As the soil, microbes, and organic matter pass through the earthworm, the invertebrate’s digestive system adds more microbes and nutrients to its digesting food. As a result, the castings are more nutritious than the surrounding soil. 

Okay, but what’s the big deal about nutritious soil? The bottom line is that worm castings improve your lawn’s soil health, which ultimately improves the health of your turfgrass. And the healthier your turfgrass, the more beautiful and robust it will be. 

  • Free and eco-friendly fertilizer: Since worm castings act as a natural fertilizer for your lawn, you’ll save money on costly commercial fertilizers and protect the environment from their harsh chemicals. 
  • Repaired topsoil: Earthworms that expel their castings on the soil surface help rebuild topsoil, the most fertile layer of soil. The planet is losing topsoil at a rapid rate due to erosion, yet topsoil is necessary for growing crops and grass. 
  • Free and nutrient-rich mulch: Don’t know what to do with the worm castings in your lawn? Rake them up and sprinkle them in your garden. Even your vegetables enjoy a health kick now and then. 

Brownie points: Earthworms offer more than just they’re castings. Earthworms have many benefits in the lawn, including thatch control and aeration.  

Benefits of worm castings for the garden

When worm castings appear in your yard, why not toss them in your garden as mulch? Your plants will love the added nutrients, and your garden soil will appreciate the health boost. 

  • Earthworm castings have a high concentration of microbes that help repel pests and soil-borne plant diseases. That means your fruits, flowers, and veggies will likely grow healthier, and you can rely less on pesticides. 
  • Castings are highly nutritious and provide food for plants, speeding up germination and producing a higher yield. 
  • When the manure exits the worm, the worm forms a mucus coating around the manure that allows the nutrients to release into the soil slowly. The worm casting is a ‘slow release’ fertilizer that won’t burn your plants like some commercial fertilizers can. 
  • Worm castings help retain moisture in the soil, which can prove helpful for plants that can’t tolerate dry soils. 

Find a balance and hire a pro

Is your lawn suffering from worm pooh blemishes, but you don’t want to eradicate the presence of earthworms? Hiring a local lawn care professional can help you strike a balance. 

Skilled in their craft, a lawn care expert can get to the root of your worm castings problem without eliminating your helpful worm population. From weekly mowings to regular maintenance, leave your lawn in good hands. 

Main Photo Credit: sarahharding | Pixabay

Jane Purnell

Jane Purnell is an artist, writer, and nature lover. She enjoys teaching readers about the importance of eco-friendly lawn care, integrated pest management, biodiversity, and sustainable landscaping.