Moss is a dense plant with no roots that grows in shaded or moist areas of a lawn, specially where other grass is scarce. It spreads by moss spores that are carried by wind and water, that quickly develop into moss growth under the right conditions. Although some gardeners prefer to grow moss as an ornamental grass, that is not always the case. Moss competes with grass for soil nutrients, and reduces the appearance of your lawn. Immediately kill moss on your grass yard to prevent it from spreading further.
Spot treat small patches of moss in your lawn. Spray a potassium salt spray to kill patches of visible moss growth. Moss exposed to this treatment usually dies in within 12 hours. You can even pour boiling water on the moss patches. Make sure, however, that moss patches are isolated and not near any lawn grass, as boiling water may cause them to wilt.
Follow manufacturer's instructions to spray moss herbicide to areas with extensive moss growth. Make sure the herbicide includes ferrous sulfate or iron that is formulated to treat moss and not lawn grass. Maintain a height of 7 to 8 inches from the moss when spraying.
Prune trees and shrubs surrounding your grass to increase the amount of sunlight they receive. Towering shrubs and trees block a lot of sunlight. Sunlight that reaches grass reduces soil moisture, which is an essential requirement for moss to thrive.
Rake the area vigorously to remove dead moss. Collect in a plastic trash bag and seal it properly before disposing it. You can even use a dethatcher to pull moss out.
Plant grass on cleared areas to prevent any moss from growing there again. To do this, aerate the compacted soil with a rented aerator and improve poor drainage or low-lying areas in your lawn by adding a layer of topsoil over it. Also test the pH of your soil and add lime according to the result. An ideal range is between 6.0 and 6.8.
Mix fescue and ryegrass seeds and plant over the bare spot. Water the seeds once a day until the soil is evenly moist, until they germinate. Plant shade tolerant grass on shady areas.