Mosses are small green plants that have thin stems and are densely covered with leaves approximately 1/16 to 1/8 inches long. Generally, moss grows together, forming a thick green mat. Moss takes away from the beauty of a well-maintained lawn and thus many homeowners wish to kill the nuisance plant.
Conditions Favoring Moss
Moss does not kill grass, but instead grows in areas where grass has become weak and thin. Consequently, moss growth is an indication that your lawn is unhealthy. Conditions that favor the growth of moss include low soil fertility, acidic soil, excessive shade, poor drainage, soil compaction, poor air circulation and excessive irrigation.
Moss can be killed using commercial moss killers, available at most lawn and garden stores. Effective moss killers include either iron sulfate or potassium salts of fatty acids. These chemicals kill moss and turn it brown or tan. Once the moss turns brown or tan, it can be raked off of your lawn using an iron rake or dethatcher. The area should then be re-seeded to prevent future growth.
While moss killers get rid of moss, it is a temporary solution. You will need to improve the health of your lawn to avoid future moss growth. You can do several things to accomplish this. Apply a fertilizer at the right time, depending on the type of grass in your lawn, and at the the proper rate. Maintain a soil pH of 6.0 to 6.8. Prune trees and shrubs to avoid excessive shade, aerate your lawn to reduce soil compaction, correct areas of poor drainage, avoid excessive mowing and watering, and make sure the grass planted in your lawn is appropriate for the specific climate.
Limestone, available at most lawn supply stores, is commonly used to kill moss in lawns. Limestone, however, raises the pH level in your soil. Thus, depending on the pH level of your soil, limestone may actually promote moss growth and damage your lawn. When applying moss killer, follow the instructions on the package. Overuse can damage your lawn and some products may stain concrete and other non-lawn surfaces.