Moss in Lawns

                        The growth of moss in lawn areas is a frequent complaint of homeowners. It is generally believed that the presence of moss is associated with acidic soil conditions, and that the addition of lime will rectify the situation. While mosses are often found on soils with low pH values, they may also become established in areas of low fertility, shade, improper drainage, and/or compaction. More often than not, two or more of these factors combine to create conditions unsuitable for vigorous turf growth.

               A soil test will determine the pH and fertility level of the soil and recommend the necessary lime and fertilizer. Only a site inspection will reveal problems due to shade, poor drainage, or compaction.

               Adverse site conditions such as compaction, poor drainage, and shade must be addressed if the area is to support a healthy lawn. Compacted soils can be loosened manually or mechanically. Localized areas of poor drainage may sometimes be improved by minor regrading. More expensive and laborious steps may need to be taken if the affected areas are extensive. Consult UM Extension's Turf IPM Facts (to order call 413-545-2717) for more information on lawn care and site preparation.

               Tree shade reduces the amount and quality of light your lawn area receives. Tree roots compete with the lawn for water and nutrients. Where tree cover is not exceptionally dense, removal of a few carefully selected lower branches may improve light conditions enough for moderate grass growth. Another option is mulching or growing plants more suitable to the site. Shade tolerant ground covers include ajuga, sweet woodruff, goutweed, lily of the valley, pachysandra, periwinkle, violets, ferns, and English ivy.

             To eliminate moss from lawn areas, it must be physically removed before reseeding. Grass seed needs to be in contact with bare mineral soil for good germination and growth. Commercially prepared moss killers are available, although their usefulness is debatable. Moss killers work in two different ways. One (Safer Brand Lawn Moss Killer Concentrate*) uses fatty acids of potassium salts which causes dehydration of the moss. Others ( ex. Sudbury Moss Master* and Scotts Moss Control Plus Lawn Fertilizer*) contain zinc, copper, or iron as active ingredients. At the prescribed dosage, these elements disrupt the metabolism of the moss plant, while not harming lawn grasses. If used extensively or during hot periods, turfgrasses, too, may be damaged. The elimination of moss plants is not a quick or easy task. Unless the underlying problems are corrected moss will continue to colonize the site.

  * When a trade name is used for identification, no product endorsement is implied nor is discrimination intended against similar materials.

NOTICE: The user of this information assumes all risks for personal injury or property damage.

WARNING: PESTICIDES CAN BE POISONOUS. Read and follow all directions and safety precautions on labels. Handle carefully and store in original containers in a safe manner and place. Do not contaminate forage, streams or ponds. Pesticides should never be stored with foods or in areas where people or animals eat.