Pender Gardener

Moles are a well-known cause of tunnels and mounds in lawns.

Moles are a well-known cause of tunnels and mounds in lawns.

Published: Tuesday, January 22, 2013 at 12:06 PM.

Dealing with Mounds and Tunnels in Lawns

Are areas of your lawn bumpy and uneven? When you walk across these areas does the soil sink or feel soft? If so, some type of soil dwelling critter is probably the cause. During winter the activity of moles, earthworms and mole crickets can cause mounds and tunnels in lawns that result in uneven or rough patches. To fix these problem areas you must first diagnose which critter is causing the damage.



Earthworms are extremely beneficial for lawns and gardens. As they tunnel through the ground they create channels that allow air and water to move into the soil and improve drainage. In addition, earthworms ingest soil and organic matter, which passes through their digestive tracks and comes out the other end as worm poop, more commonly referred to as worm castings. Worm castings are an excellent source of nutrients for plants and are sometimes sold as a natural fertilizer.

Earthworms are active near the soil surface during fall and winter, particularly when the ground in wet. As a result, their castings can build up in mounds that resemble small anthills. To determine if earthworms are causing the mounds in your yard, look at the size of the soil particles. The soil from mounds caused by ants and burrowing insects is usually very fine, composed of individual soil particles or sand grains. The soil from mounds created by earthworms is clumped into pellets that resemble Nerds candy, except they are the color of soil.

High earthworm populations are more common in moist, heavy soil. In these soils, worm castings can sometimes build up an inch or more deep, particularly in winter when the lawn is not being mowed. The good news is the earthworms and their castings almost never cause damage to the lawn and there is no need to try to get rid of them. If castings become thick in an area of your lawn simply rake them out or collect them and use them as a natural fertilizer in other areas of your yard.

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