Moss is a type of weed that often takes advantage of conditions which inhibit the thick growth of grass. Moss does not kill grass, but instead is opportunistic and takes advantage of any dead or thinning spots in your lawn and asserts itself. The real key to getting rid of lawn moss and keeping it out of your life is to do whatever is necessary to encourage the thick, luxuriant growth of grass, preventing moss from ever gaining a foothold in the first place.
Rake your lawn with a thatch rake in the fall or early spring while the moss is dormant. Rake thoroughly, raking up as much of the moss as possible as well as any dead grass. Scoring the top of any bare spots with the rake is a plus, as this gives the new grass seed a better chance to get started.
Choose a grass seed based on the conditions of the mossy area. If the area is shaded, choose a grass that grows well in shade. Consult a local nursery to find the right type of grass for your lawn conditions and your geographic area.
Spread the grass seed on the area where you have recently removed the moss. Spread the seeds according to the manufacturer's instructions, using a seed spreader, if applicable.
Spread approximately 1/2 inch of organic manure on top of the grass seed. Use a manure spreader or use your hands or a shovel.
Soak the seeds with approximately 1 inch of water for the first watering, and then keep the soil damp but not soggy for 21 days following seeding. Your grass seed should sprout within seven to 14 days, depending on the type of seed and weather conditions.
Set your mower to 2 1/2 to 3 inches and mow the new grass 21 days after it has sprouted.