Many regions of the country have mild, wet winters which promotes moss growth in lawns. Around the world there are only a dozen known lawn moss species, according to the Oregon State University. Each fall, when the rains begin, the moss starts to flourish and continues its growth cycle until spring. Lawns are dormant and at their weakest during the winter months so moss readily invades and takes over the region. A healthy, well maintained lawn is better equipped to resist the presence of moss. Regularly fertilizing lawns helps prevent moss invasions. Once moss becomes established there are several means of control.
Dethatch lawn moss using a lawn flail dethatcher in March or April. Dethatching the lawn will remove approximately 75 percent of the the actively growing moss from the lawn, according to Oregon State University.
Apply cryptocidal soaps to lawn after dethatching. Apply at a ratio of 2 1/2-quarts per 1000 square feet of lawn. Follow the directions on the label for application. The soaps are safe for use around sidewalks and foundations.
Fertilize the lawn using a general purpose lawn fertilizer that contains iron. Iron helps to kill the moss and prevent regrowth. Follow the directions on the label for application. Apply with care because iron will often stain sidewalks and other concrete or rock surfaces. Use a fertilizer spreader for even distribution.