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Moss in Lawns

Several species in the Pacific Northwest
Updated Sep 30, 2022
 
1

Make a Positive Identification

Moss in lawns stands out from grasses. It has a different color and texture. Moss species in the Pacific Northwest include Dicranoweisia cirrata, Bryum capillare, Brachythecium albicans, and others.

Species: Moss in Lawns
Closeup of moss and grass mixed

Weston Miller, Oregon State University

Moss grows in lawns when the conditions favor it. Shade from trees or structures, poor soil drainage, and low soil pH all promote moss growth.

Species: Moss in Lawns
Close-up photo of moss in lawn

mtreasure, iStock

Moss mixes with grasses to form a dense ground cover. Unlike grasses, moss in lawns doesn’t require regular mowing.

Species: Moss in Lawns
Moss covering lawn in shady area

Weston Miller, Oregon State University

Moss will take over shady lawn areas. It forms a dense mat. Moss-dominated lawn areas require less mowing and care than a grass lawn.

LOOK-ALIKES: LIVERWORTS
Species: Liverworts
Liverwort plants

Liverworts grow in moist environments with mosses.

Helpful

They are usually not a problem and can be left alone.

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2

Moss in Lawns Benefits

  • Moss grows throughout the Pacific Northwest.
  • It covers surfaces and provides habitat.
  • Moss absorbs water. It has a role in nutrient cycling and erosion control.
  • It’s used as an indicator of air pollution.
  • The moist environment of a shaded lawn is ideal for moss growth. Mosses mix with grasses to form a dense, easy-care ground cover.
 

Moss in Lawns Risks

  • Moss becomes a problem when people want a manicured look for their lawn.
  • Moss in lawns doesn’t hold up to high traffic such as sports activities or as a dog run.
Risk Card
Does it cause harm?
Adults & Children
None
Property
Low
Pets
None
Annoyance
Some
Environment
Helpful
Action Optional
 
3

Take Action?

Moss is common in lawns. People have varying opinions about it.

Do I need to take action?

  • What are your expectations for your lawn?
  • Keeping moss from growing in lawns requires ongoing effort when conditions favor moss growth.
  • If moss growing in your lawn is unacceptable, follow the recommendations described in this article. Otherwise, ignore moss in your lawn. It will spread over time.
  • Consider renovating your lawn if it has a lot of moss and you don’t like how it looks. See Practical Lawn Establishment and Renovation  (OSU Extension Service).

What if I do nothing?
Under shade, moss and grasses grow together to form a low-maintenance, dense mat.

NEED HELP?

Consider a licensed pest control company. Learn How to Hire a Pest Control Company.
Your local Extension Specialist in Oregon  and other states  can suggest other methods.

 
4
Solutions for Moss in Lawns
  • Remove moss with a rake or similar tool. Expose the bare soil.
  • Consider using a moss killer (mossicide) product to kill the moss. Then remove the dead moss to expose the soil.
  • Cover the exposed area with a lawn patch product. Or sprinkle lawn seed and apply mulch. Water as needed until the grass seeds sprout.
  • Care for your lawn: Mow and water regularly. Fertilize at least one time per year in the fall. For manicured lawns, fertilize in the spring and summer as well.
  • Allow increased sunlight on the lawn by removing overhanging tree branches.
  • Apply lime to increase the soil pH, if needed.
  • Aerate the soil to improve drainage.

Jump To

Method Does it work? Is it safe? Recommendation
A
Physically Remove
Somewhat effective
Low risk
Recommended
B
Moss Killer (Mossicide) Products
Somewhat effective
Moderate risk
Use if Necessary
C
If Using Moss Killer, Protect Yourself & Minimize Risks
D
Prevent Moss in Lawns
 
A

Physically Remove

Non-Chemical Method

Grahamphoto23, iStock

Physically Remove

Recommended

Remove moss with a rake or other tools to expose the soil. Reseed the area or use lawn patch.

Does it work?
Somewhat effective

Removing moss and replanting grass keeps moss out for several years. Use preventive measures for best results.
How much effort?
Moderate effort
What's the risk?
Low risk
Possible risk of exposure or harm from chemicals
NONE
  • Mow the remaining grass short, if needed.
  • Scrape the moss out of the lawn. Use a rake, dethatching rake, or power dethatcher.
  • Expose the bare soil. Leave the grass you want to keep.
  • Cover the exposed soil with lawn patch product or seed.
Metal rake with pile of moss removed from lawn

Grahamphoto23, iStock

Remove the moss with a rake or dethatching rake. Or rent a power dethatcher.

Closeup of rake with exposed soil, moss, and grass

Weston Miller, Oregon State University

Remove all the moss and expose bare soil.

Bag of lawn patch product on grass with product spread out over a bare area

Weston Miller, Oregon State University

Cover exposed soil with a lawn patch product. These products combine seed, fertilizer, and mulch.

Seeder with seed on lawn

Weston Miller, Oregon State University

Another method is to sprinkle lawn seed and add mulch on top. Water the area to germinate the grass seed.

 
B

Moss Killer (Mossicide) Products

Chemical Method: Use with caution

Weston Miller, Oregon State University

Moss Killer (Mossicide) Products

Use if Necessary

Chemical treatments are short acting. They control existing moss, but don’t provide long-term moss control.

Does it work?
Somewhat effective

You will still need to rake out the moss from your lawn. Use preventive measures for best results.
How much effort?
Moderate effort
What's the risk?
Moderate risk
  • Moss-killer products (mossicides) come with real risks. ALWAYS read the entire label front to back. Use a magnifying glass.
  • Mossicides can run off your site into waterways and may harm wildlife. See How to Keep Pesticides Out of Waterways.
Possible risk of exposure or harm from chemicals
Using moss killer (mossicides) includes some amount of risk. The lowest risk comes with using alternative methods.

You may be exposed to a mossicide if you:

  • Get it on your skin
  • Breathe it in
  • Eat or smoke afterward without washing hands
  • Touch or eat plants that are wet with spray (you, pets, or children)
  • Bring it inside on your shoes or clothes

Follow directions closely to reduce risk.
  • Mow the remaining grass short, if needed.
  • For best results, follow the label instructions for moss-killer products.
  • You still have to scrape the dead moss out of the lawn. Expose the bare soil and reseed.
Mossicide product for use on lawns, decks, and roofs

Weston Miller, Oregon State University

Moss-Killing Soap & Citrus Oil

  • Products that contain moss-killing soap and citrus oil (d-limonene) effectively kill moss.
  • These products are biodegradable and non-corrosive.
  • Avoid overspraying on adjacent plants. Rinse off overspray.
  • Don’t allow runoff that contains moss control products into storm drains or waterways.
Iron-based lawn product

Weston Miller, Oregon State University

Iron Products

  • Iron-based lawn products effectively kill moss in lawns.
  • Products are corrosive and toxic to humans, pets, landscape plants, and aquatic animals.
  • They stain concrete.
  • Don’t allow runoff that contains moss control products into storm drains or waterways.
 

If Using Moss Killer, Protect Yourself & Minimize Risks

Chemical Method: Use with Caution
Pacific chorus frog

"Frog (Pacific Chorus Frog?)" by Ingrid Taylar is marked with CC BY-NC 2.0.

Mossicides can move into waterways and harm aquatic life. They can damage nearby plants.

Why is it important to read moss killer labels?

  • They have detailed information on how to use the product correctly and legally.
  • They contain information on potential hazards of the product.
  • They provide instructions you should follow for poisonings and spills.
  • Following label instructions helps you to minimize the risks and maximize the benefits.

Key Moss Killer Safety Tips

  • Read the entire label front to back. Follow the instructions.
  • Review the instructions even for brands you know.
  • Moss-control products often require goggles. Glasses are not sufficient.
  • Only apply the product where the label says it may be applied.
  • Be precise in your application. More is not better.

The Label is the Law

ALWAYS read the label before using mossicide products. The label is a legal document that provides information on how to safely use the mossicide. This helps avoid harm to human health and the environment. Using a mossicide in off-label ways is illegal. It can result in legal enforcement actions.

READ THE LABEL & Follow Instructions
It has instructions to protect you and the environment.

  • Labels are different for every product and they often change over time.
  • Use a magnifying glass.
  • Pay attention to CAUTION, WARNING, and DANGER statements.
  • Pay attention to the PRECAUTIONARY STATEMENTS.
  • The law states you must read and follow mossicide instructions.

Avoid Wet, Windy or Hot Weather
Use during favorable weather for best results.

  • Don’t use when it’s raining or when rain is expected in the next 24 hours. Mossicides can wash into waterways and harm aquatic life.
  • Wind causes spray and dust to drift that can get on you and desired plants.
  • Don’t let the spray or dust contact plants that you want to keep.

Protect Yourself
Eye, skin & lung irritants

  • Wear the right protective gear. This often includes chemical-resistant gloves, safety goggles (safety glasses often not enough for mossicides), a long sleeve-shirt, pants, socks, and shoes.
  • Take care not to inhale the dust.
  • Wash hands after applying and before eating or smoking.
  • Take a shower immediately after handling mossicides.
  • Wash clothes worn while mixing or applying separately from other laundry.

Protect Children & Pets
Children and pets are risk if they eat or touch treated areas before mossicides dry.

  • Keep them away during and after applying mossicides (read label for how long).
  • Remove toys and pet dishes from yard before applying.
  • Don’t track mossicide products into home on shoes or clothes.

Storage & Disposal

  • Store in a secure storage area away from children.
  • Don’t put unused mossicides products in the trash. Take them to a hazardous waste facility.
  • Never pour product down any drain or waterway.

Call  1-800-CLEANUP (1-800-253-2687) to find out where to dispose of mossicides.

For the Portland metro region in Oregon, contact Metro’s Recycling Information. Call  503-234-3000, email   or visit Metro’s website  

More about:

About Using Pesticides on School Grounds in Oregon

If using pesticides on school grounds, there are special rules in Oregon. See School Integrated Pest Management  (Oregon Department of Agriculture).

NEED HELP?

The National Pesticide Information Center (NPIC)  can answer questions about pest control chemicals.
 1-800-858-7378 or npic@ace.orst.edu  

Consider using a licensed pest or weed control company. Learn How to Hire a Pest Control Company.

Your local Extension Specialist in Oregon  and other states  can suggest other methods.

 

Prevent Moss in Lawns

Healthy, dense stand of turf grass

OSU Turfgrass Management Program

Grow a Healthy Lawn
  • A healthy lawn resists invasion by moss, weeds, insects, and diseases.
  • Plant grass species best suited for your area.
  • Plant disease-resistant cultivars or mixtures.
  • Lawn grasses require full sun to thrive. Lawns grown in shady areas will require more care to maintain to high standards. Or you may tolerate moss, which will likely grow in shady areas.
  • Apply fertilizer and water to grow a lawn that matches the lawn standards you wish to maintain.

 

How to Prevent Lawn Problems

If your lawn area favors moss growth, annual maintenance is required to keep it from growing.

  • Maintain the appropriate growing conditions for strong, healthy lawn grasses. Healthy lawns resist moss problems.
  • Lawns change over time. After lawn seed has been sown or sod laid, a mixture of desired lawn grasses and broadleaf weeds, grassy weeds, and moss will evolve.
  • Soil drainage, soil fertility, sunlight, water stress, and how the lawn is cared for and used will affect how your lawn looks over time.
  • Set realistic expectations for your lawn. Match the lawn standards you want to maintain with the correct maintenance schedule.

See Prevent Lawn Problems for details.

MOSS ON ROOFS & WALKWAYS

Content provided by editor Weston Miller and writer J. Jeremiah Mann. Pesticide safety information edited by Kaci Buhl.

 Reviewed by OSU Department of Horticulture.

Photo of Weston Miller

Weston Miller

Project Founder and Content Writer

Weston Miller served as Community and Urban Horticulture faculty for Oregon State University Extension Service for Clackamas, Multnomah, and Washington Counties. Weston is an author for content for this website. He developed funding partnerships with Portland area agencies to initiate and build out the Solve Pest Problems website focused on this goals:

J. Jeremiah Mann

J. Jeremiah Mann

J. Jeremiah Mann completed a Physical Science undergraduate degree at Humboldt State University, and M.S, Ph.D focusing on plant science topics at UC Davis. He went on to work for the Natural Resources Conservation Service and in a leadership position serving a private agricultural technology company. He currently lives in Sacramento California where he consults on pest and property management topics.

Photo of Kaci Buhl

Kaci Buhl

At the state level, I lead the Pesticide Safety Education Program (PSEP). The program hosts live recertification events around the state, serving over 1,000 licensed pesticide applicators each year. We also produce web-based training modules and license-preparation study manuals. Special training for unlicensed pesticide applicators is also available through a grant from the USDA Specialty Crop Block Grant Program. The PSEP at OSU works closely with the Oregon Department of Agriculture's Pesticides Division.

Moss in Lawns References

Managing Moss in Lawns in Western Oregon  
OSU Extension Service

Lawn and Turf Moss  
PNW Disease Management Handbook