Mosses are tough little plants that multiply quickly when the growing conditions are right. They spread without roots or seeds, and can quickly take over just about any surface, from hard surfaces like driveways and paths, to your lawn. Native mosses exist in almost every climate, so it is easy for these mosses to thrive in their natural environment where you prefer to have grass.
To describe mosses as tough is an understatement. Without roots, they are adapted to live with very little water. They can absorb moisture from the air, and can go for years with so little water they turn brown and appear to be dead. At the same time, they can thrive in soil so wet that other plants' roots are damaged. They also do well in shade.
When a lawn is not healthy because the conditions for growth are not quite right, mosses can move in. The most common conditions that inhibit grass from being healthy are poor drainage, overly wet soil and shade. Compacted soil also makes it hard for grass to grow well.
The most permanent way to get rid of moss in your lawn is to change the conditions that make your lawn unhealthy and give moss a chance to get established. If your soil is damp all the time from poor drainage, you can install a drainage system or reshape the ground to promote better drainage. In shady areas, trim branches back and remove lower branches to let more light in. You can also plant a shade-tolerant grass in shady areas. If your soil is compacted, add amendments over time, such as peat moss, to lighten the soil.
It is difficult to get rid of moss if the poor growing conditions for grass are not changed, so improving the conditions should be your first line of attack. You can remove moss by raking it up and disposing of it. Anything left in the soil, though, will grow and spread. You can spread desiccants, like limestone, or fungicides, like copper sulfate, on the moss to suppress it. You can also spray a solution of lemon dish-washing detergent and water on the moss to inhibits its growth. Use 1 oz. of detergent for each quart of water. While these suppression methods will slow the spread of the moss, it is nearly impossible to get rid of it unless you correct the growing conditions
Homeowners put out time, effort and money to prevent moss from overtaking their grass. Yet, many horticulturists suggest encouraging the moss to take over. If your yard conditions are right, you can convert a lawn that requires watering, fertilizer and maintenance to a soft, drought-tolerant moss carpet that will maintain itself.