Moss grows in a lot of lawns, especially ones that are shaded, compacted, or acidic. Moss isn’t harmful, but too much of it can kill grass and make your lawn look patchy and unhealthy. This article will look at the connection between moss and lime and ask if adding lime to lawns can help get rid of moss.
What Causes Moss in Lawns?
Moss thrives in conditions that are unfavorable for grass growth. Some of the main things that cause moss to grow on lawns are:
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Excess Shade Grass needs at least 4-6 hours of direct sunlight per day Too much shade promotes moss growth
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Compacted Soil: Compacted soils restrict air and water movement, creating the moist conditions moss prefers.
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Acidic Soil: Moss favors acidic soils with a pH below 6.0. Most grasses grow best at pH 6.0-7.0.
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Poor Drainage: Standing water or chronically wet areas are ideal habitat for moss.
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Low Fertility: Moss moves in when grass is weakened by insufficient nutrients.
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Cutting the grass too short keeps the roots from growing and makes the lawn too thin, which lets moss grow in.
Why Apply Lime for Moss Control?
Lime does not kill moss directly, but by raising the pH of the soil, it makes it less likely for moss to grow. Most lawn grasses do best in soils that are slightly acidic to neutral, with a pH range of 6 to 8. Moss likes acidic soils. 0-7. 0.
Applying limestone raises the soil pH, making conditions better suited for healthy grass growth and less hospitable for moss. By promoting thicker, vigorous turf growth, lime helps crowd out existing moss and prevent its return.
How Does Lime Affect Moss Growth?
Lime affects moss growth in several key ways:
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Raises Soil pH: This corrects one of the main factors that allow moss to thrive.
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Improves Nutrient Availability: Increasing pH improves availability of essential nutrients like nitrogen, phosphorus, and potassium for improved grass growth.
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Reduces Aluminum Toxicity: High levels of soluble aluminum in acidic soils can be toxic to grass roots. Lime binds aluminum into insoluble compounds.
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Provides Calcium: Calcium is an essential plant nutrient. Limestone supplies calcium for stronger grass plants.
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Improves Soil Structure: Added calcium promotes soil particle aggregation for better aeration and drainage.
When to Apply Lime for Moss Control
Lime can be applied anytime moss is present, but the best timing is early fall or spring. This gives the lime time to react in the soil before the main growing season. Allow at least 2-3 months for the lime to increase soil pH.
Lime should be applied at least 2-4 weeks before or after using other moss-killing treatments. Otherwise, the lime may interfere with the efficacy of chemical moss killers.
Avoid applying lime in summer when high temperatures can burn grass. Limestone particles may also blow away before infiltrating the soil if applied during dry, windy conditions.
How Much Lime to Apply for Moss?
A soil test is recommended to determine exactly how much lime is needed to raise the pH for your specific lawn. In general, 50 lbs of limestone per 1000 sq ft is a typical application rate when the goal is moss control.
On lawns with severe moss problems, higher application rates up to 100 lbs/1000 sq ft may be warranted to increase pH quickly. Use ground limestone rather than pelletized lime, as it begins working faster.
Will Lime Completely Eliminate Lawn Moss?
While lime creates less favorable growing conditions, it may not completely eliminate all moss, especially if other contributing issues are not also addressed.
The best moss control results will be achieved by applying lime in conjunction with other practices:
- Dethatching/raking – Removes moss so grass can regrow
- Aerating – Alleviates soil compaction
- Moss killers – Chemical/organic products that damage existing moss
- Fertilizing – Encourages thicker, competitive turf
- Overseeding – Fills in bare spots to prevent moss regrowth
- Pruning trees – Improves sunlight penetration
Should Lime be Applied Before or After Moss Killer?
Most experts recommend treating moss with chemicals or physical removal before applying limestone. Existing moss may create a barrier preventing the lime from fully reaching the soil. Removing moss allows the lime to have full contact with the soil.
If lime is applied first, wait 2-4 weeks before using other moss treatments. Letting the lime start increasing pH gives it time to weaken the moss, improving treatment effectiveness. Avoid applying lime and chemical moss killers at the same time.
Choosing the Right Lime for Moss Control
Not all limestone products are equally effective for moss control. The best options include:
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Calcitic lime or regular garden lime – Contains mostly calcium carbonate. Quickly raises pH.
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Dolomitic lime – Calcium + magnesium carbonate. Provides magnesium needed by grass.
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Fast-acting lime – Extra finely ground particles act more quickly.
Avoid:
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Hydrated or slaked lime – Can burn grass if over-applied.
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Pelletized lime – May not breakdown quickly enough to effectively control moss.
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Bypass bagged lime – Often contains impurities that reduce efficacy.
Always check soil pH again after several months to determine if additional lime is needed to reach the desired pH level.
The Bottom Line
While lime itself does not kill moss, raising the soil pH with limestone applications creates an environment less hospitable to moss growth. Lime improves conditions that allow grass to better out-compete moss. Addressing other issues like poor drainage and compacted soils is also key for the best moss control in lawns.
How To Prevent Moss
If you want to prevent moss from taking up residence, make your lawn less hospitable to the weed. The best way to do this is by resolving the issues that may have led to the moss in the first place.
The precise amount of sun your lawn needs will depend on your region and grass type. On average, most lawns need about four to six hours of sunlight per day. If branches are casting a shadow over a large area of your lawn, prune them back. You can also switch to growing a grass that tolerates shade better, like tall fescue.
Send a sample of your soil to a university or your local cooperative extension. They can test the soil to determine if it has the proper nutrients and whether it’s alkaline enough. In general, a lawn’s pH level should be between 6. 0 and 7. 0. To make your lawn less acidic, you can apply lime. Soil amendments and regular fertilization are the key to a healthy lawn.
Drainage issues welcome moss. The type of soil you have can impact the likelihood of drainage issues—clay soil tends to puddle. However, you can amend the soil to make it easier for moisture to pass through.
Too much foot traffic and thatch can pack down your soil, making it unable to keep nutrients, water, and air moving through it. If you use a tool or machine to poke thousands of tiny holes in your lawn to let it breathe, you can fix this problem. Dethatching, or breaking up the layer of decomposing organic matter between grass blades and the soil, will also alleviate this issue.
Why do I have so much moss in my lawn?
If you have a lot of moss in your lawn, the likely culprits are excessive shade, poor soil drainage, soil compaction, or a low soil pH.
Get rid of Moss in Lawn – How To
FAQ
What will kill moss but not grass?
There are several ways to kill moss without hurting the grass. These include using iron-based moss killers, dish soap solutions, or baking soda. This Old House says that iron sulfate is something that is often found in moss killers and is safe for grass.
How long does lime take to kill moss?
If you plan to spread lime on your lawn, allow at least two weeks from when you treated it for moss and weeds.
What kills moss instantly?
To kill moss quickly, you can use products containing potassium soap, ferrous sulfate, or fatty acids, which will dry out and kill the moss. Alternatively, vinegar, especially when combined with dish soap, can damage moss cells, causing them to die.
What is the best moss killer for lawns?
The best moss products to use for this are:Lawnsmith Green-up Ferrous Sulphate. Ferrous Sulphate with Fertiliser – Lawnsmith Winter Green. MossOff Chemical Free. Lawnsmith Green-up Ferrous Sulphate. MossOff. Lawnsmith Winter Green and Miracle-Gro Mosskill. Green-up Ferrous Sulphate. Lawnsmith Winter Green.