University of Illinois Extension
Bruce Spangeberg

These articles are written to apply to the northeastern corner of Illinois. Problems and timing may not apply outside of this area.

Stateline Yard & Garden

Various Reasons Moss Invades Lawns

November 8, 2001

In cleaning up leaves in the yard this fall, perhaps you noticed areas where moss has invaded. While typically thought of a shade lawn problem, there are various reasons why moss may develop into a problem. Analyzing the problem now can make it easier to correct next season.

An important first step in dealing with the problem is to recognize moss does not invade thick, vigorous grass, but develops as lawn areas thin out. Potential causes include low soil fertility, poor soil drainage, compacted soils, excessive shade, poor air circulation, and high humidity. Often the site may have a combination of these conditions.

In addition, poor lawn care practices are another source of moss problems. General neglect, irregular mowing, lack of fertilizer, and overwatering are common problems leading to poor turf growth, that may in turn lead to moss problems.

What can be done to solve moss problems in lawns? Moss can be eliminated, at least temporarily, by hand raking when it first appears. Ferrous ammonium sulfate or ferric sulfate (iron sulfate) can also be used to control moss. The moss will temporarily burn away, but tends to return fairly quickly unless the site conditions and/or lawn care program is altered.

Looking ahead to the 2002 season, it's best to focus on the cultural options for a more permanent answer to moss problems.

Evaluate the site and make all necessary corrections to favor lawn growth. For example, prune trees to allow more light to reach the lawn and remove excess vegetation to improve air circulation over the site. Reduce soil compaction using cultivation practices such as core aerification. Make adjustments as needed to lawn care practices of fertilizing, watering, and mowing. Finally, make sure the proper grass is growing for the site conditions present.


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