Homeowners usually prefer their lawns to be an expanse of grass uninterrupted by other plants, but moss, like many other plants, seems to enjoy the company of grass and will often thread itself through the lawn uninvited. If conditions are to its liking, it may crowd and shade out the grass, but often the problem is that the grass needs more sun and a less acidic soil with better drainage and aeration.
Lawn Grass and its Cultivation
Lawn grass likes sun, well-drained soil with a neutral pH and lots of high-nitrogen fertilizer. New leaves sprout from the base of the plant, close to soil level. While grass can be cut frequently, taking off more than one-third off the top of the leaves reduces the vigor of the grass.
Grass varieties differ in their tolerance for shade, cold, heat and drought and in their season of best growth. Fescue, for instance, grows well in cool weather but will go dormant when the temperature climbs; bluegrass requires warm days to break its winter dormancy.
Moss and its Growth
Moss is a primitive plant with stems and thin leaves, only one cell thick, but without true roots. Some species are less than 1/2 inch tall with thick, velvety texture. Others, lawn mosses among them, grow into a loose mat of intertwined stems 2 or 3 inches high.
Moss grows best on moist, acid soil, even tolerating soggy, poorly drained conditions. It will tolerate sun but is happiest in partial to full shade.
Common Problems That Can Encourage Moss
Where moss is found in the lawns, the usual reason is that the grass is under stress and lacks vigor, leaving thin, bare areas that can be colonized by weeds. Wet, acid, compacted soil, lack of fertilizer, shade and extra-low mowing are the main causes of unhealthy lawns. These conditions all favor moss and it will take advantage of the invitation.
Removing Moss from a Lawn
It is possible to remove moss from a lawn by physically raking it out, either by hand or with a machine, and chemicals containing various iron compounds are available to kill the moss before raking. A permanent solution to the problem, however, requires the removal of the underlying conditions that are stressing the lawn grass followed by practices that preserve its vigor and health.
Wet soil should be drained, overhanging trees trimmed to reduce shade, ground limestone applied to raise the pH of the soil and fertilizer applied at the recommended times for your area to get the grass growing strongly. Mow the lawn at a height of 2 or 3 inches.
Creating a Moss Lawn
On the other hand, if existing conditions favor the moss, you can turn the problem into an asset by weeding out the grass and leaving the moss as your groundcover. It will often be thick enough to suppress weeds on its own and you can encourage it by applying extra water during the summer the first year.
This is an especially good solution for areas under trees whose shade will increase as they grow. The smooth texture of the moss is an attractive contrast to shrubs and perennials and provides the same expanse of green as a grass lawn without the effort of mowing.