Moss does not develop in healthy lawns. Lack of fertility, soil compaction, poor drainage, shade, and poor soil aeration are the most common causes of moss in lawns. Moss is not directly harmful to grass. However, it occupies bare spots in the lawn as the grass population thins. The acidity of the soil has little to do with whether moss is present.

If your lawn area is moist and shady, you will have difficulty controlling moss, because you have an ideal moss environment. Moss is often troublesome in spring, when temperatures are cool, and soil moisture is high.

When moss grows in an area where you would expect good turf to prosper, the problem is usually low fertility and soil compaction. Fertilize and aerate the soil, to improve these conditions. Prune trees and shrubs to allow more light to reach the soil, and to improve air circulation. Competition from grass will help keep moss out.

Copper sulfate at the rate of 5 ounces in 4 gallons of water, per 1,000 square feet, kills moss. The moss will return after treatment, unless you correct its causal factors. Unless your lawn is particularly acidic, lime is generally unnecessary. The acidity of your soil can be determined by a reliable soil test.

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