Earthworm castings on moss

Dear David Spain,

I have been encouraging moss in my backyard and following your tips for a regular watering schedule. I can really see a big difference in the growth of the moss since I started and we are getting very excited with the results. The trouble is that there’s often many earthworm castings on the surface that are an eyesore and difficult to remove. What do you recommend to deal with this annoying problem. Thank you in advance for your help.



Dear James,

You are not alone in this problem. The reason that earthworms sometimes leave behind their castings above the surface is a direct correlation to the amount of moisture in the soil.  As the soil becomes saturated with water the worms will migrate towards the top layer of soil. The cure is to reduce watering volume, ensuring the ground does not become saturated. If you are using a sprinkler system, adjust it’s settings to reduce the run time or frequency. Light and frequent waterings are beneficial for moss growth but watering too much is only a waste of water and can promote other problems such as earthworm castings or slime molds.

There are a couple of techniques to remove the worm castings after they appear. One is to let them dry out completely, this will allow you to crumble the castings without causing a mud cake on top of the moss. Another is to use a knife to slice off the tower of the casting pile and discard, moisten the remaining casting and allow it to soften, then using a pump sprayer, concentrate a jet stream directly on to the pile and dissolve it. Using a sprayer instead of a water hose will minimize the amount of water needed to dissolve the small spot without saturating the ground and beginning the cycle all over again.

Creating the proper conditions for moss growth is a balancing act. We can create an environment that will allow moss to grow at an increased rate, but we must be careful to not create the conditions for undesirable side effects.  Happy mossgardening.

David Spain, a.k.a. Moss Rock


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By: Helen Yoest

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