Managing Moss in the Landscape
In the spring of the year, many homeowners say to themselves: “THIS is the year I will get the lush, green lawn I’ve always wanted!” However, this ambition is frequently thwarted by many challenges, such as weeds, mole hills, and patchy spots. Moss in the lawn is another regular sources of frustration. Homeowners often believe the moss is “killing” their grass and they want to know how to kill the moss, thinking this will allow the grass to grow back. In fact, moss is not killing the grass. The moss is growing because the environmental conditions in that area will not allow grass to grow, while those same conditions are conducive for moss.
Moss in the landscape is the result of any one, or often, combination of factors. These factors are: acidic, low fertility soils, shade, moisture, and soil compaction. Without first determining which factors are causing the moss to grow, and correcting those conditions, the moss will eventually return. The following are steps to correct conditions that support moss and encourage grass instead.
- The first task is to determine if the soil pH and nutrient levels will support turfgrass. Take a soil sample; this will provide information as to how much lime and soil nutrients should be added for grass to grow. Soil sampling materials and information are available at the Cooperative Extension office. The North Carolina Department of Agriculture performs the tests, which are free from April 1 through November 30 (the tests are $4 from December through March). In addition to applying needed soil amendments, determine if the area receives sufficient light to grow grass. The most shade tolerant turfgrass requires at least 50% sunlight for a minimum of 4 hours a day for adequate growth. Zoysiagrass is more shade tolerant than bermudagrass, which has the highest light requirement of turfgrasses. Some trees, such as oak, provide shade too dense for grass to grow beneath the canopy. Additionally, tree roots compete with grass for water and nutrients. If shade is a problem, in some cases removing lower tree limbs or thinning shrubs to increase light penetration and air movement can allow sufficient sunlight to support grass. However, trees add a great deal of value to the landscape as well, so consider carefully before sacrificing trees to grow grass.
- Another problem contributing to moss is soil that is frequently wet. Determine if there is a drainage issue, such as a gutter spout spilling onto the lawn, or run-off from a driveway, causing water logged soils. If so, installing drainage tiles to move water away from the site, or creating a swale above the area to keep water from washing down, may rectify the situation. Soils which receive water run off are also frequently compacted; foot traffic and parking on the lawn are other causes of soil compaction. Turfgrass, and centipedegrass in particular, cannot grow well in compacted soils. Aerate the soil to reduce compaction; lawn aerators are usually available for rent from local hardware stores. Spring is an optimum time for this task.
- Moss can be controlled with copper or ferrous sulfate sprayed at 5 ounces in 4 gallons of water per thousand square feet. If seeding a lawn in the area, be sure to de-activate the copper sulfate with 5-10 pounds of limestone; copper sulfate is toxic to seedlings. However, controlling the moss without rectifying the conditions will result in poor grass stands and the eventual return of the moss.
- If all else fails, or if conditions do not allow for modification, there’s always the “if you can’t beat ‘em, join ‘em” solution. In Japanese culture, moss gardens are considered highly desirable and are cultivated with great care. There are landscape businesses in this country devoted to moss and it’s use. Moss, once established, requires little in the way of irrigation and weeding, and, of course, never needs to be mowed.
When one weighs all that is involved in taking care of a grassy lawn, a moss lawn may be the best alternative after all.