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We have received many queries from people concerned about mud balls appearing in their lawns? What are they? Are they in fact a cause for concern?

If your soil has a healthy population of earthworms then you may start to find small mounds of soil or mud balls on your lawn. These mud balls are the castings which have passed through the earthworms the previous night and have come to the surface as tunnels that are created below the surface of your lawn. Since they are more common in Spring and Autumn due to the optimum soil moisture and temperature for earthworms, it’s not surprising that people are reporting this issue now.

Earthworms are great in that their activity acts as a natural aeration of the soil beneath your lawn but there is also a down side to a large population inhabiting your lawn. The mud balls are quite slimy in texture as they contain soil and the natural secretions from the earthworm’s digestive system. Sitting on the surface of the grass will allow them to be smeared across the lawn during general traffic and mowing. The end result is a potentially very muddy and slippery lawn; the castings also create the perfect environment for weeds to germinate and take hold during next spring.

Lawn varieties like Sir Walter Buffalo are less susceptible to mud ball damage but earthworms can cause more issues in a Couch lawn.

At Daleys Turf, we don’t recommend using a pest control treatment to deal with earthworms, as they do a great job aerating and making the soil healthy. But there are a few ways that you can reduce their activity in a natural way.

Organic matter is a fantastic source of food for worms, so any dead and decaying matter left on the lawn will encourage them and increase their activity and therefore the amount of castings on your lawn. Rake up and remove autumn leaves that have fallen from deciduous trees and use a catcher when mowing, so that the grass clippings aren’t left on the lawn to increase the amount of organic matter and the moisture level in the soil below.

Heavier clay soils and wetter soils with an abundance of bacteria and soil flora and fauna are also encouraging to earthworms, so you can ensure that their activity is limited by having soil that is not too wet. Look at the drainage of your lawn and reduce the amount of watering in periods with consistent rainfall.

You can also rake sweep casts off the lawn using a stiff broom, rake or bamboo cane, but this option may not be very efficient should your lawn contain numerous amounts of castings. This should be undertaken when the castings are quite dry to eliminate the possibility of smearing the castings and making a giant mess of the lawn.

Just remember that earthworms are actually a sign of a healthy lawn. They help in breaking down thatch, increasing decomposition and create useable nitrogen in your soil. Five or more earthworms per square foot of soil provide your lawn with 25% of its seasonal nitrogen needs. As the moisture levels reduce the earthworms will bury deeper into the root system, just as before and you won’t even notice them continuing on with their great work during winter.

This Post Has 4 Comments
  1. Hi. I believe I have these worms on my lawn but it seems to be an unhealthy level as I have very hard lumps all over my lawn when it’s dry which become slimy, gooey mud patches when wet. I’m not sure how it got to be so many but need to find a way to reduce thevamount ifvwirm actuvity since my lawn is no longer enjoyable. Any suggestions?

    1. Sounds like you may need to incorporate some drainage to your lawn area, the worms are only trying to survive in those conditions.

  2. Can Lawn Grubs Do Something Similar? I have a blue couch lawn and an abundance of castings in an area that has lawn grub activity by the appearance of the blue/red flying waspy like inscents and colour of the lawn.

    1. I don’t believe lawn grubs do the round mud balls, it’s most likely you have lawn grubs and earthworms together.

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