Earthworm activity is on the rise as soils warm up, but their mounds will be highly visible until grass starts growing in late March and April. Earthworms are highly beneficial because they create channels for air and water penetration, reduce thatch, and tend to increase the fertility and health of a soil. However, some will complain that earthworm casts cause a lumpy and hard- to-mow lawn. Plus the casts tend to smear and create a mess on golf course fairways, greens, and tees. To overcome this, casts can be broken up with raking or with mowing after they have dried. A pull-behind sweeper might be perfect for this job on a homelawn. Cast problems can be further minimized by creating a dense turf through proper fertilization in the fall, mowing at 2.5 to 3.0 inches or more, and irrigating as needed. Many question if there are pesticides that are available that will kill earthworms, but no pesticides are labeled for earthworms and thus it is illegal to apply a pesticide with the sole intent of controlling earthworms. The University of Kentucky has a very nice publication listing various pesticides and their effect on earthworms.


Zac Reicher, Professor/Turfgrass Extension Specialist/ Purdue University

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