Moss grows in lawns for a number of reasons. Heavy shade, wet areas or poor soil conditions are some of the main environmental causes in which moss will thrive. Moss can be eradicated by herbicides or other chemical means. However, the most effective method is to reestablish the lawn area back to a state of health for the grass species. Improving the soil under the turf grass will effectively choke out the moss.
Improve the amount of sunlight reaching the moss-infested area by pruning overhead tree limbs. Allow areas of sun to illuminate the growing moss during the day. This does not mean to denude the tree; prune limbs to create gaps in the overhead tree canopy.
Attach a thatching blade to your lawn mower. Follow the manufacturer's directions for attachment and operation. Run the thatching blade over the mossy area. Vigorously rake the moss thatch, with the garden rake, to remove. Place the moss in a compost pile to decompose.
Rent a lawn aerator in place of thatching the lawn. The aerator will remove small plugs of soil from the ground and redeposit the plugs on top of the soil. The lawn aerator improves soil drainage.
Seed the thatched or aerated soil with a shade-tolerant grass species. Consult your local agricultural extension service for shade grass species in your area and climate. In most cases, a ryegrass perennial or blend will grow well in shade and moist areas.
Layer ½ inch of potting soil or sand over the new grass seed. Keep the newly-seeded area moist.
Mow the new grass seedlings once the blades reach a height of 3 inches. Keep the grass mowed to approximately 2 inches high.
Apply an approved moss herbicide if all else fails. Follow all label directions for mixing and application. Herbicides come in various strengths.
Spray the moss in either late winter or early spring when moist, cool conditions exist for the plant.