Moss is one of the most common types of weeds that invades home lawns. It can be controlled by altering the soil environment to create the most favorable conditions for grass to grow. Moss is very adaptable and can grow in difficult conditions. Moss does not kill grass, but it does create unfavorable soil conditions for grass growth. These conditions, not the moss, cause the grass to die.
As the grass dies, the moss moves in and thrives. To eliminate moss from growing in your grass you must determine the cause of the unfavorable soil conditions and improve them. This will encourage grass growth to compete with the moss over time. Treating the symptoms with chemicals that kill moss will not correct the factors that allowed the moss to grow in the first place and the moss will return.
Soil Conditions Unfavorable to Grass
Poor soil fertility: Test soil for nutrients. Make sure your lawn is properly fertilized. Grass needs nutrient rich soil to become firmly established and maintained. Moss can grow in nutrient low conditions and will thrive in the space where the grass can’t be sustained. Make sure to fertilize your lawn regularly.
Low soil pH: Don’t guess, have you soil tested. Moss is capable of thriving in acidic soil conditions. Have your soil professionally tested or use a store bought kit and follow the directions for increasing the pH to the proper level.
Heavy shade: One solution may be to plant shade friendly grass in low light areas. Another option is to eliminate grass in these areas. Ornamental flower and shrub beds can be created and shade-loving plants added. A different approach is to remove tree or tree branches to increase the amount of sunlight and circulation to the area. Trim back foliage. Remove fencing or install open weave fencing.
Poor drainage: Where this occurs can be seen by observing your lawn during or after a rainfall. If there are pools of water that remain, this condition can be corrected by creating better drainage. You can begin by filling in the low spots, installing drain tiles or French drains. This will move the excess water into areas where poor drainage is not an issue. The area may then need to be reseeded. Irrigation also plays a factor and may need to be improved.
Compacted soil: This will prevent root growth and can be improved by perforating the soil and aerating more often. This should be done in the spring or fall, when the lawn is not under stress. It also should be done when the soil is not to wet. You can improve the moisture retention and condition of the soil by working in coarse sand or a an organic material. This can be aided by a rototiller.
Chemical Treatments for Moss
Ferrous ammonium sulfate is the most common chemical used in products designed to kill moss. It usually comes with a spay bottle. After saturating the moss affected areas, wait for the moss to turn black. This should take anywhere from a few hours to a full day. Using an iron rake, rake out all the dead moss. Then the bare areas should be reseeded and covered with topsoil.
Although moss can be a pesky nuisance to your lawn, eliminating it and preventing its return should be a long term goal but is possible with some work, time and patience.