Having moss in the lawn is a common problem. Lawns that are thin or mismanaged are a ripe breeding ground for the common moss. Proper care of a lawn is usually enough to manage and prevent the formation of lawn moss, which can hinder grass growth and give your lawn an undesirable patchy look.
A pH test helps determine the nutrient composition of the soil and determines whether the moss might be due to a nutrient deficiency. A pH test can be bought from gardening centers in powder and vial form, or as an electrical instrument that uses probes to test the electrical composition of the soil, which is affected by nutrients. A pH test will indicate whether fertilization and lime are necessary to balance the soil and reduce moss.
Moss is susceptible to sulfates, which burn the moss away. Ferrous ammonium sulfate or ferric sulfate (iron sulfate) are effective in reducing moss growth in the lawn and removing patches that have appeared. Unfortunately, the effects of sulfate are temporary if the lawn is not properly managed.
Thatch is the collection of dead, dried grass on the top layer of a lawn's soil. Thatch kills existing grass and reduces the likelihood of new grass growth. Moss is likely to grow in areas where grass is thin, so the removal of thatch is integral to keeping a lawn dense. A standard rake, or dethatching rake, run along the surface of the lawn will break up thatch. The removed thatch is excellent for composting material.
Moss grows well in shady areas that do not dry after rains. Plants that provide shade in a mossy area should be cut back, or pruned so more light pours through the canopy. Pruning also improves air circulation, which helps dry wet areas quickly. Different types of grass are resistant to shade and moisture and will remain dense in those conditions. These varieties should be planted if sun coverage and air circulation are impossible to improve.
Mowing is an effective deterrent and treatment for moss, but only if done properly. Cutting grass too short causes thinning and burning. Keeping it too long keeps grass from drying out, increasing moss production. Different grass varieties require certain cutting lengths, but as a general rule, most grasses require between 2 to 3 inches, otherwise the grass is stressed. Grass is best cut in thirds, meaning one third of the grass blade should be cut at a time.