These articles are written to apply to the northeastern
corner of Illinois. Problems and timing may not apply outside of this
Moss Problems in Lawns
Have Various Causes
March 16, 2000
Moss growing in lawn areas is a common problem that can have several
causes. Keep in mind, however, moss is not likely to invade or crowd out
vigorous grasses. Instead, moss develops as lawns thin due to poor site
or management factors.
While we usually think just of shade, there are several problems that
may allow moss to develop in a lawn. These 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.
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 about the moss? 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.
It's best to focus on the cultural options for a more permanent answer
to moss problems in lawns. 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 to lawn care practices. For example, fertilize according
to the type of grass growing on site and type of site. Lawns in full sun
require more fertilizer than those in shade. Avoid excessive watering
and mowing too short. Mow between two and three inches, preferably at
the high end of the range for summer.
Finally, make sure the proper grass is growing for the site conditions
present. Kentucky bluegrass is ideal for full-sun areas but does not typically
do well in shade, thus tends to thin out and allow moss to invade. Fine
fescue, such as red fescue, is a better option for shade. If fine fescue
declines, consider a shade tolerant groundcover.