Moss in Lawns

Moss, a native plant, commonly grows in areas where turfgrass does not thrive. Mosses move into areas of thinning turf because the growing conditions favor the moss over turfgrass. In some cases, moss is an attractive groundcover and it is perfectly suitable to let it grow.

Conditions that favor the growth of moss

The appearance of moss usually indicates you have a number of these conditions present in your yard.

• Low soil fertility
• Acidic soil
• Shade from trees and shrubs
• Areas of poor drainage
• Soil compaction
• Excessive irrigation
• Poor air circulation
• Lack of lawn care
• Inappropriate choice of turf species or cultivars for site conditions

Lawn care practices that help to prevent/manage moss

Lawn care that encourages a healthy lawn will not only reduce your problem with moss but will produce a lawn that can out-compete weeds as well.

• Maintain soil pH for optimal turf growth (6.0 - 6.8) by applying lime according to soil test results. Have your soil tested every 3 years. 
• Prune trees and shrubs to allow more sunlight in and to improve air circulation. Do not “top” trees but thin branches that prevent light from reaching the turf.
• Aerate by renting a core aerator that removes plugs of soil from the turf. Aeration should be done in the fall on cool-season turf like tall fescue and in mid to late spring on warm-season turf like zoysia.

• Correct areas of poor drainage by filling in low lying areas with topsoil and reseed. 
• Irrigate lawns only if necessary.
• Plant the proper grass species for the site conditions. For growing grass in shady areas plant fine fescue, which tolerates less sunlight. This species of grass is not good for high traffic or poorly drained sites. Tall fescue will tolerate moderate shade but grows best when it receives a minimum of 4-6 hours of direct sunlight.
• Remove thatch. Thatch build-up accumulates in zoysia, Kentucky bluegrass, and fine fescue lawns. It reduces the vigor of turf by forming a mat that reduces the amount of water, air, and nutrients reaching the soil. 
• Mow lawn to the proper height.
• Fertilize according to the chart below.

Maryland lawn fertilizer schedule

A bag of lawn fertilizer applied according to label directions will provide no more than 0.9 lbs. of nitrogen per 1,000 square feet. Measure your yard before buying fertilizer

 * According to the MD Lawn Fertilizer Law, fertilizer cannot be applied between Nov 15th - March 1st.

• Grasscycling or leaving grass clippings to naturally break down on a lawn contributes about 25% of the total yearly nitrogen needed to keep grass healthy.&   
• Older, established lawns may only need one fertilizer application per year. 
• Apply fertilizer in the fall if fertilizing once a year. 
• Optional fertilizer applications may be needed if the lawn is less than 2 years old or is thin, weak, or grass blades are yellowing. 

Moss management

For a more permanent solution, you need to correct the conditions that favor moss growth. Both of these methods will provide temporary control only.

• Rake the areas covered in moss with a steel rake until the moss is removed and bare ground is exposed. Reseed the area.
• Products available to kill moss can be purchased at hardware stores, farm supply stores, and garden centers. Typically, the active ingredients are iron sulfate or potassium salts of fatty acids. Both of these materials are drying agents that will burn the moss and turn it brown or tan. Rake up the dead material and reseed the area. Use products according to the label directions.

Alternatives to grass

Consider converting the areas to ornamental beds or plant a groundcover, if conditions cannot be altered. Once established, groundcovers may require less maintenance than grass. Moss itself is considered a low-maintenance groundcover.

Moist shade

• Pachysandra procumbens (Allegheny spurge)
• Chrysogonum virginianum (Green-and-Gold)
• Ferns
• Hostas spp.
• Pulmonaria spp. (Lungwort)
• Galium odoratum (Sweet Woodruff) 

Dry shade  

• Carex pensylvanica (Pennsylvania sedge)
• Polystichum acrostichoides (Christmas fern)
• Epimedium spp.
• Symphytum (Comfrey)

By Debra Ricigliano, Maryland Certified Professional Horticulturist, University of Maryland Extension Home and Garden Information Center (HGIC), 2019. Reviewed and edited by Jon Traunfeld, HGIC Director and Christa Carignan, HGIC Coordinator, Digital Horticulture Education.
Based on HGIC publication HG 100 Moss in Lawns.