Lawns and Moss: Causes and Corrective Measures
Moss is a common problem in many home
landscapes. The home gardener may spend
many hours and a great deal of money in an
attempt to control it. The results are few if
the cultural conditions that favor moss are
not understood. Cultural conditions
favorable for moss growth include one or
more of the following:
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insufficient sunlight due to shade,
an acid or sour soil (low pH),
low soil fertility,
a heavy or compacted soil
soil conditions that are too wet.
In the home lawn, the usual cause of moss
growth is insufficient sunlight to support the
turf grass. When the shade is caused to trees
or shrubs, it may be possible to increase
sunlight to the turf grass by pruning and/or
removing some of the plants to allow more
light to the area.
Acid soil conditions (low pH) are often
blamed for the presence of moss. Many
gardeners will make rather heavy annual
applications of limestone in an attempt to
kill it. If conditions are favorable, i.e., heavy
shade and/or moist-to-wet soil, moss will
grow quite nicely on limestone. Have the
soil tested before applying limestone. For a
soil nutrient analysis including pH, submit a
one cup soil sample to the Home and Garden
Education Center, Room 4, U-4115, 1380
Storrs Road, Storrs, CT 06269-4115. There
is a $5.00 charge for the service.
Soil with low fertility levels will not
produce a vigorous turf. Weak, thin turf will
provide niches for plants with lower nutrient
demand to become established. Mosses have
a low demand for nutrients. A soil test will
determine the levels of the major nutrients.
The soil test report will suggest amounts of
nutrients to apply to correct any
shortcomings which could have prevented
good lawn/turf grass growth.
Heavy or compacted soil, as well as
excessively wet soil, will have low oxygen
levels. Oxygen is necessary for good turf
grass root growth. Compacted soils can be
aerated with a spoon or core-type aerator.
Heavy soils (soils with a high clay or silt
content) have a tendency to become
compacted and waterlogged. An
improvement in texture and aeration can be
made by tilling a few inches of coarse, sharp
sand into the existing soil. A few inches of
decomposed organic matter will also help.
Where the clay content of the soil is high,
tilling in 100 pounds of calcium sulfate
(gypsum, land plaster) per 1,000 square feet
could aid in improving the structure of the
soil. Well-structured soil is usually well
aerated.
Where the soil is wet for long periods of
time due to a high water table or a shallow
hardpan layer, it may be necessary to drain
the offending water or grow plants suitable
to the site. The installation of drain tiles
and/or curtain drains should only be done by
persons knowledgeable in their installation
and familiar with the legal requirements.
Rough bluegrass, Poa trivalis, can be
planted in wet sites because of its tolerance
to wet and shaded sites.
Moss can be eradicated by mechanical or
chemical methods. Raking with an iron rake
or scraping will remove the moss. An
application of one of the moss control
products which contain potassium salts of
fatty acids (DeMoss*) or iron sulfate found
in commercially available moss control
products will give short-term control of
moss.
Killing the moss and failing to correct
cultural conditions that favored moss growth
will only result in its reinvasion. If it is
impossible to correct the conditions,
consider keeping the moss as a permanent
low maintenance groundcover or plant
another groundcover, pachysandra, English
ivy or myrtle, which are shade tolerant.
Prepared by: Edmond L. Marrotte, Consumer Horticulturist, Department of Plant Science,
University of Connectict, Reviewed by UConn Home and Garden Education Center, 2005.
The information in this material is for educational purposes. The recommendations contained are based on the best
available knowledge at the time of printing. Any reference to commercial products, trade or brand names is for
information only, and no endorsement or approval is intended. The Cooperative Extension system does not
guarantee or warrant the standard of any product referenced or imply approval of the product to the exclusion of
others which also may be available. All agrochemicals/pesticides listed are registered for suggested uses in
accordance with federal and Connecticut state laws and regulations as of the date of printing. If the information
does not agree with current labeling, follow the label instructions. The label is the law. Warning!
Agrochemicals/pesticides are dangerous. Read and follow all instructions and safety precautions on labels.
Carefully handle and store agrochemicals/pesticides in originally labeled containers immediately in a safe manner
and place. Contact the Connecticut Department of Environmental Protection for current regulations. The user of
this information assumes all risks for personal injury or property damage. Issued in furtherance of Cooperative
Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Kirklyn
M. Kerr, Director, Cooperative Extension System, The University of Connecticut, Storrs. The Connecticut
Cooperative Extension System offers its programs to persons regardless of race, color, national origin, sex, age or
disability and is an equal opportunity employer