What can I do about the worm casts on my lawn?

By | 04/03/2012
Worm cast in a lawn

Worms work their way through the soil, breaking down organic matter. A worm cast occurs on the surface of the soil and is a small mound of muddy soil ejected from the digestion system of some species of these earthworms. Some lawns can have a large amount of worm activity.

Worm activity in the winter can be a problem for many types of lawns. If you are the proud owner of a fine, ornamental lawn, worm casts may spoil the look and cause it to become lumpy and uneven. If you use your lawn as an additional room of the house enjoy the outdoors, then worm casts in autumn and winter can be a problem. They are stepped in, causing a muddy patch, and the mud can be trampled into the house or spoil your new shoes. These patties of soil are also fantastic seed beds for weeds, moss and all the other nasties that you have been spending all the previous year trying to eliminate!

An earthworm on a lawn
An earthworm

Worm casts on your lawn

The problem is that worms are great for your soil. They make their way through the soil, digesting the goodness and breaking down organic matter. They also create channels in the soil which helps to aerate the soil. We really don’t want to kill the worms, or stop them from performing their valuable service on your soil.

By regularly inspecting your lawn and just sweeping away worm casts as you find them will tackle the problem. Once a week, walk your lawn. Using a stiff household broom or a long flexible cane, simply brush the casts aside. This will spreading out the topsoil which has been pushed to the surface. This will allow the grass beneath to poke through and see the sun. Done regularly, this will help keep your lawn looking smooth throughout the winter months.

There are some worm control products available on the market, but I don’t recommend them as they can harm worms.

Kris Lord

6 thoughts on “What can I do about the worm casts on my lawn?

  1. Michael Maxwell

    I cannot let my grass grow longer as my problem is on a bowling green.

    1. Kris Lord Post author

      A bowling green is a sports surface, not a domestic lawn.
      Try using a dew switch for greens worm cast control.

  2. Michael Maxwell

    Our regular greensman moved house ( and our bowling club ) 2 years ago. Since then after many abortive attempts to employ a new one, the job was foisted upon myself. The worm problem, which has always been with us, has now become much, much worse. I am only an amateur greensman and need help to improve the state of our green. Any advice would be very welcome.

    1. Kris Lord Post author

      Hi Michael,
      Greens maintenance is different to domestic lawns as you are aiming for a smooth, hard playing surface not just healthy grass.
      Worm cast control is always difficult on greens as there are no chemical controls available any more.
      I recommend the old fashioned of “switching” the lawn. Google “dew switch”. This is a rather labour-intensive method of sweeping the lawn, but it will give you a good surface and control the casts when done in the right conditions.
      Good luck!
      The Lawn Man

  3. Phil Sykes

    Whilst I appreciate that worms are meant to be helpful for soil, in many cases (sadly) this is not the case for many lawns. I have battled with lawn worms year after year and have finally had to concede defeat. Worms (when plentiful) on a general “utility” type lawn are a disaster. During late autum when the lawn remains damp, wormcasts cannot be brushed away. On a lawn where regular access is required the surface can become a mudfield. Once the cold and damp /wet season is over the renovation job begins. When i get the lawn back to a reasonable condition, it’s time for the worms again. I give in!!

    1. Kris Lord Post author

      Let your lawn grow a lot longer during the autumn and winter, it will allow the worms to do their important work and they won’t bother you so much.


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