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617.678.5553 (E. Kingston, NH)
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Moss Invasion in Progress!
Moss can kill an entire lawn!
Causes of Moss Incursions
Moss thrives in lawns where the conditions aren't optimal for healthy grass growth, particularly when there's excess moisture, low light, compacted soil, or acidic soil. It also can flourish when lawns have poor drainage, are over-watered or have inadequate mowing.
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Poor Drainage:
Moss loves wet environments and poor drainage allows water to collect on the lawn surface, creating the perfect breeding ground for moss.
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Compacted Soil:
Compacted soil doesn't allow for proper drainage and aeration, further contributing to wet conditions and making it easier for moss to take hold.
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Acidic Soil:
Many types of moss prefer acidic soil and a low pH level can discourage healthy grass growth, allowing moss to thrive.
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Excessive Shade:
Areas with limited sunlight can also be an ideal environment for moss as it doesn't require much sunlight to survive.
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Overwatering:
Excessive irrigation can saturation the soil and create conditions that moss loves.
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Inadequate Mowing:
Mowing too short can stress grass, weakening it, and making it more susceptible to moss invasion.
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Low Fertility:
A lack of essential nutrients in the soil can weaken the grass allowing moss to compete more effectively.
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Thatch:
A buildup of thatch, the layer of dead and decaying organic matter on the surface of the lawn, can trap moisture and create a haven for moss.
Treating Moss Incursions
To treat moss in a lawn, address the underlying conditions that encourage its growth. Methods include scarification to remove existing moss, aerating the soil, adjusting the pH of your lawn, improving lawn drainage, and using chemical or organic moss killers. Additionally, you can prune trees and shrubs which may be creating an over-abundance of shade on the lawn. Once the moss is removed, ensure the lawn is properly fertilized and re-seeded to promote healthy grass growth.
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Have your soil tested to determine its current pH level and apply lime (pelletized) with a spreader to mitigate the existence of overly acidic soil and bring it to a level that's more ideal for grass and less ideal for moss. The ideal lawn pH for grass is between 6.2 and 7.0 . Moss's preferred pH is between 5.0 and 5.5 but it can exist and prosper at pH levels that are more amenable to grass growth.
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This page is more dedicated to using chemical or organic moss killers along with the overall moss treatment topic and doesn't go into detail about addressing the contributing factors for moss invasions.
QuickSilver
QuickSilver is a herbicide and effectively eliminates silvery moss along with many broadleaf weeds. It's very expensive with current pricing at ~$188 for an 8 ounce bottle however a little goes a VERY long way. At the recommended strength, 1 to 2 ounces of QuickSilver will eliminate moss from an acre of lawn. Our testing shows that it eliminated the moss in our sprayed area effectively while not harming the grass in the same area. (Our supplier informed us that it kills moss spores but we weren't able to verify this statement.)
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However, due to its strength, it's recommended that a dedicated sprayer be used for applying QuickSilver since some ornamental plants are highly susceptible to its active ingredient (carfentrazone-ethyl). Because of this, we do not want our hydroseeder used for application of QuickSilver.
Moss Out!
Moss Out is a liquid moss killer which contains ferric sulfate and effectively eliminates moss on contact. (Previously it was available in a granular form that ​you would apply using a spreader but we didn't find this form to be that effective.) A one gallon bottle of the liquid form can eliminate moss from 2000 square feet of lawn.
However, at ~2.7 fluid ounces per gallon, it takes a long time to apply Moss Out to a large area. It took us about 10 to 15 minutes to mix and apply one gallon; spraying 2000 square feet requires 48 gallons of mixture. (At ten minutes per gallon, that's eight hours to treat 2000 square feet.)
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Because of this, our hydroseeder is IDEAL for applying Moss Out! You can fill it with 48 gallons of water, mix in the Moss Out, and spray all 49 gallons (about half a machine tank) in less than 30 minutes! Since the machine has a 100 gallon tank, you can make a double batch using two gallons of Moss Out and treat 4000 square feet of moss covered lawn in under 50 minutes which would take about 16 hours spraying by hand. Additionally, the wide spraying area of the machine makes it far less likely for any moss to be missed than when done by hand.
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Lawn Treated by Moss Out!
Moss Out applied by hand spraying. Missed sections of moss can be seen; coverage is uneven; some moss areas only partially treated as can be seen by a light brown rather than dark brown / black color. Total time to spray this small area, 10 to 15 minutes.
Moss Out applied by one of our hydroseeders. No missed sections; coverage is even; moss is fully treated as can be seen by a dark brown / black color. Total time to spray this, much larger area was about a minute.