Moss can make a lawn look uncared for. It can also be a sign that the lawn is in an unhealthy state. The problem with simply removing moss from a lawn is that there can be several different causes. Even though it is relatively easy to remove the moss, if the underlying causes of the problem are not addressed, the moss is likely to return. The most common causes for moss are poor soil, highly acidic soil, not enough fertilizer, heavy shade or excessive moisture. Another excellent condition for moss is soil that is too compacted for water to soak into it.
Spray the moss-affected area with copper sulfate, available from your local garden center or any home improvement center. Once the moss has died (it will turn orange or brown), rake the area thoroughly with a hard steel-tinned rake to remove all of the dead moss.
Run an aerator over the affected area. Poke holes into the ground at least three to four inches deep. Holes should be a minimum of four inches apart.
Spread lime on the affected area. Use four to six pounds of lime per 1,000 square feet of affected area.
Spread a nitrogen-based fertilizer on the soil. Spread approximately four pounds of nitrogen fertilizer per 1,000 square feet of lawn.
Trim trees and shrubs as much as possible to increase the amount of sunlight reaching the lawn. Excess shade is often a cause of moss growth.
Spread shade-tolerant grass seed on the affected area, and gently rake the seed into the lime and fertilizer. Water lightly with a sprinkler, getting the soil damp but not wet. Remember, too much water is part of the problem, although aerating the soil, as in Step 2, should help eliminate that problem.
Allow new grass to grow. Keep the ground damp but not wet. Allow the area to dry slightly between waterings. Do not mow the new grass until it is at least 21 days old.
Set your lawnmower to cut your grass at least 2½ to 3½ inches high. This will help prevent new moss growth as well.