Moss in yards has been a common complaint this spring. It occurs in sun or shade, alkaline or acidic soils and in wet or dry sites. Moss is very adaptable and can grow in difficult conditions. In poor sites, the moss moves in as the grass dies out.
The easiest way to eliminate moss is to rake it out of the affected areas and alter the conditions responsible for its presence. If moss is occurring in a shaded area, consider planting the area with shade tolerant grasses such as creeping red fescue, chewings fescue or hard fescue. If the fine-leafed fescues have failed, perhaps it is time to consider alternative shade tolerant groundcovers rather than grass. Surrounding trees may need to have their lower limbs removed or the crown of the tree thinned to allow more light penetration. Remove unnecessary shrubby undergrowth as well.
When moss occurs in a sunny location, consider fertilization practices. Even low-maintenance lawns need one or two fertilizer applications a year to grow well. In some cases the soil may be compacted and need aeration as well. Soil testing will provide the soil pH. Grass grows optimally at a pH of 6.8 to 7.2 which is close to neutral. Many people automatically assume the soil is acidic when moss occurs and want to add lime. Iowa generally has alkaline soils and liming can make matters worse. A soil test will eliminate the guesswork.
Materials, such as copper sulfate, do eliminate moss in lawns. Use these products according to the label directions. However, copper sulfate only cures the symptom, the moss. They do not change the conditions responsible for its presence. When moss occurs in the flower bed or vegetable garden, simply rake off the moss and till the area. Once normal (sunny and drier) weather makes another appearance, moss growth should slow and disappear.
This article originally appeared in the May 12, 1995 issue, p. 64.