How Earthworms Help Your Lawn and Soil

close-up of am earthworm on moss and pavement

Earthworms may feel a little slimy, but their reputation in the lawn is far from it. In fact, once you learn how earthworms help your lawn and soil, you might start to encourage them.  

Earthworms are essential for a healthy lawn. These invertebrates help improve soil fertility, improve drainage, and encourage root growth. But remember, it’s possible to have too much of a good thing. Does that mean earthworms have their disadvantages, too? Read on to dig up the secrets. 

Benefits of earthworms

After a big rain shower, you might see pink worms wiggle their way up to the soil’s surface. Their presence is a good sign your lawn has healthy soil (and healthy soil is the secret to growing a healthy lawn). 

So, how are these earthworms benefiting your lawn and soil? Are they really crossing off yard work tasks from your to-do list? Here’s what these hardworking worms can do: 

Boost soil fertility

Just as you need to eat your fruits and vegetables to feel strong and healthy, your grass requires essential nutrients, too. Earthworms add nutrients to the soil, which helps your grass grow healthy.  

Sure, you can douse your lawn with fertilizer four times a year, but that’s not good for the environment. Why not enjoy free, eco-friendly fertilizer provided by worms who actively increase soil fertility? You’ll save cash on fertilizer, and your soil will thrive without much intervention. 

Earthworms improve soil fertility in a number of ways: 

  • Nutrient-rich worm castings: Earthworms move through the soil consuming organic matter and microorganisms. As the soil and organic matter passes through their digestive system, it becomes concentrated with more microorganisms and nutrients. As a result, the worm castings (aka worm poop) are richer in nutrients than the surrounding soil. 
  • Natural fertilizer: According to the Soil Association, worm castings contain 5 times more nitrogen, 7 times more phosphorus, and 1,000 times more beneficial bacteria than the original soil. Nitrogen and phosphorus are essential nutrients for growing healthy turf and are in most commercial fertilizers.  
  • Rebuild topsoil: Earthworm castings help rebuild topsoil, the most fertile layer of soil. Topsoil is necessary for growing crops and grass, yet the planet is losing topsoil rapidly due to erosion
  • Nitrogen booster: Dead worms quickly decompose, which adds more nitrogen to the soil. 

Improve soil structure

Do puddles form in the yard after you water the grass? It’s a sign your soil is struggling. Earthworms can help with that. 

Here’s how: As worms tunnel through the soil, they improve the soil’s structure by loosening the compacted soil in a process called aeration. The tunnels encourage the movement of water, nutrients, and oxygen. 

Not only will the soil drain faster, but the grass roots also have better access to water. Soils without earthworms can drain up to 10 times slower than soils with earthworms. 

Break down thatch

Earthworms are talented decomposers that help control thatch buildup in your yard. Thatch is the accumulation of dead and living organic material between the soil’s surface and the grass blades. 

A thin layer of thatch is good for the lawn, but a thick layer invites pests and diseases and blocks water and nutrients. Earthworms help keep the yard’s thatch layer in check by snacking on it. 

Encourage root growth

As earthworms create tunnels in the soil, they also create space for the grassroots to grow deeper. 

Soil without earthworms is often compact and has little space for the roots to grow. Soil compaction encourages a shallow root system, which isn’t healthy for your lawn. Shallow roots make your turf susceptible to pests, disease, and drought. 

The bottom line: Earthworms help your grass develop a deep, healthy root system. 

Food for wildlife

Earthworms are an important part of the food chain. If you want chirping songbirds and croaking frogs to visit your yard, an earthworm buffet is a must. 

How do you encourage earthworms?

Having earthworms in your lawn sounds like a pretty good deal. But if your yard doesn’t have any worms, how can you get them to move in? First, you can start by lowering the rent, and then try the following: 

  • Amend your soil so that the pH is between 6.0 and 7.0 (this is also the ideal pH for growing grass). 
  • Give worms organic matter to eat. Sprinkling compost across the lawn as a topdressing is a great way to add more organic matter.
  • Reduce your use of pesticides. Pesticides can harm worms and negatively affect their reproduction. 
  • Perform soil aeration. Worms need oxygen, and they won’t find it in compact soil. 
  • Protect worms from drought and keep the soil moist. 
  • Avoid tilling the soil. 

Can you buy worms? Yes, you can buy worms at garden centers, bait shops, and pet supply stores. You also can have them delivered to your door when you order from Amazon. 

Keep in mind that buying and adding worms to your lawn won’t do any good if you haven’t prepared the right soil conditions. The worms won’t survive long if they don’t have water, oxygen, or a food source. Once you prepare the right conditions, buying the worms might be unnecessary at that point, as they’ll likely arrive on their own. 

What are the cons to earthworms in your soil?

More often than not, the presence of earthworms is a great benefit to the yard. But sometimes, too much earthworm activity can be too much of a good thing. Here’s why: 

  • Worm castings (aka worm waste) appear as small piles of soil on the yard’s surface. A few piles here and there are easy to ignore, but too many castings can ruin your lawn’s look and feel and make lawn mowing difficult. 
  • A high earthworm population might attract pests to your yard, such as moles and gophers. If you live in the southeastern part of the United States, be on the lookout for hungry armadillos. Moles, gophers, and armadillos can quickly tear up the yard as they search for a delicious earthworm treat. 

FAQ about earthworms in your lawn and soil

Do worms hurt or harm your grass?

Earthworms don’t threaten grass health, unlike grubs, which harm your turf by feeding on the roots. Earthworms prefer to eat soil and the thatch layer between the soil and grass blades. 

How can I control worm castings in the yard?

If worm waste piles are a problem in your lawn, here are some ways you can deal with worm castings all over your yard: 

Rake or sweep the castings away when they’re dry. 
Don’t overwater. Overwatering can encourage the worms to rise to the surface. 
Keep your mowing height high. Tall grass can help cover the castings. 

How can I control worms in my yard? 

When your soil has too many earthworms, the best thing you can do is make your lawn less hospitable or manually remove them. 

Pick them up after heavy rainfall and put them elsewhere, like your compost pile (composting with worms is known as vermicomposting). You might also be able to sell the worms to your local garden shop. 
Remove the tasty thatch layer with a dethatcher. 
Introduce a natural enemy, such as birds. Birds love to snack on worms. Adding a bird feeder to the yard can help attract them. 
Never control worms with pesticides. You don’t want to wipe them out completely, and pesticides aren’t good for the soil’s ecosystem. 
Remove grass clippings after mowing; otherwise, leaving organic matter on the lawn will encourage worms. 

Are worms good for garden soil?

Yes, earthworms are incredibly beneficial for your garden. They encourage good soil health and plant growth the same way they create healthy soil for your grass. 

When to hire a lawn care pro

Earthworms can’t wiggle you out of every wrong lawn problem. They’re a significant help, but your lawn still needs you to take care of it. From mowing the lawn to spreading fertilizer, maintaining a healthy lawn keeps away pests and diseases. 

But who wants to spend their weekends raking worm waste and removing thatch? Hire a local lawn care professional who will take the to-do list off your hands so you can do what matters most. While a pro keeps your lawn pristine, you’ll finally have the time to take that weekend fishing trip –– don’t forget the fishing bait! 

Main Photo Credit: catarina132 | Pixabay

Jane Purnell

Jane Purnell is a freelance writer and actor in New York City. She earned her B.A. from the University of Virginia and enjoys a warm cup of French press coffee.