3 Easy Steps to Killing Moss in Lawns

Updated on May 31, 2018
eugbug profile image

Eugene is an avid gardener and has been passionate about growing things for nearly 40 years. He also has a keen interest in DIY.

Source

How to Kill Moss on Your Lawn

Moss in a lawn competes with grass, looks unsightly and can cause heart ache for your lawn mower as it struggles to cut through the thick growth at the start of the season. Some people like daisies, moss and other wild flowers spread throughout their lawn. However if your are puritanical like me about your lawn and believe only green grass should grow in it, you will likely want to eradicate moss. Fortunately it is easy to treat and measures can be taken to prevent it growing in the first place.

Moss looks nice on trees, but do you want it growing in your lawn?
Moss looks nice on trees, but do you want it growing in your lawn? | Source

What Causes Moss in Lawns?

Moss thrives in damp and wet, cool conditions.

  • Bad drainage - If the underlying soil is compacted and clayey, and doesn't drain well, it can remain excessively wet after rainfall
  • Topology of the Lawn - If your lawn isn't flat and at the bottom of a slope, or has slightly hollow shaped sections like a saucer (the whole lawn could be like this), water will tend to collect. This in addition to bad drainage can make the lawn excessively wet
  • Lack of Nourishment - If you don't feed the lawn, moss can out compete grass
  • Shade - Sun tends to dry out the lawn and reduce the effects of water logging. However in the shade of buildings or under trees, moss can thrive in low light conditions while grass struggles. You may have noticed this in a forest where conditions are damp and moss grows on trees but very little grass is to be seen
  • Climate - There's not much you can do about this. If you live in a country which has a mild climate and lots of rain, moss can be a serious problem although growth will stall somewhat during long dry spells during the summer

How Do I Prevent Moss?

  • Feed the lawn using a composite lawn feed which contains nitrogen, phosphorus and potassium (NPK). Alternatively if you want to go organic, you can apply a handful of bone meal per square yard in the fall. This is a source of phosphorus. In the spring, apply well rotted, crumbly leaf compost or leave the clippings on the lawn every second time you cut the grass. Either of these methods return nitrogen to the soil.
  • Scarify the lawn using a rake or electric scarifier - This pulls out all the dead vegetation and helps to remove moss
  • Improve Drainage and Aeration - Use a hand fork and drive it down into the ground at 1 foot intervals. Alternatively you can use a hollow tine aerator. This tool has a series of hollow tubes rather than prongs. When you walk on it with your foot and drive it down into the ground, it removes cores of soil when pulled back up. A gas powered version of this is also available. Forking the lawn also improves aeration, as it opens up the ground, allowing more air in around the roots of grass. This helps to promote stronger, more vigorous growth of roots

Forking a lawn at 1 foot intervals helps to aerate and improve drainage. Drive the fork fully down into the ground
Forking a lawn at 1 foot intervals helps to aerate and improve drainage. Drive the fork fully down into the ground | Source
Give your lawn a thorough rake. This helps to remove moss and dead vegetation
Give your lawn a thorough rake. This helps to remove moss and dead vegetation | Source
An electric scarifier makes light work of removing moss and other dead vegetation from lawns.
An electric scarifier makes light work of removing moss and other dead vegetation from lawns. | Source

How to Treat Moss in a Lawn?

You can treat moss using a chemical called iron sulphate (also known as sulphate of iron. In US English, sulphate is spelled sulfate). It can be spread as a dry powder, however personally I find it's much more convenient to spray it or use a watering can, and this gives better coverage than spreading dry powder by hand which can produce patchy results. When you spray iron sulphate, moss turns black within about 20 minutes, so it's easy to see whether you missed any spots.

Iron sulphate will stain clothes, hands and everything else brown, and the dry dusty powder can irritate eyes. When sprayed, It will stain concrete and tarmac (asphalt or blacktop) to some extent ( sort of a beige color) so you might consider alternative chemicals as a treatment on these materials. Vinegar, bleach or salty water will burn moss and can produce good results. Boiling water also scalds moss and weeds. If you spray iron sulphate solution, the resultant stains are not as bad as those which result from scattering the dry powder.

Once you treat your lawn with iron sulphate, the moss will turn black and also the grass to some extent. This is why it's best to spray in the spring. Firstly you will have dealt with all the moss growth which accumulated over the winter, and secondly any staining of the grass will be eradicated once you start mowing your lawn again.


When Do I Treat Moss in a Lawn?

Ideally in late autumn, winter or early spring so that grass doesn't have any competition when it starts to grow again in spring.

What Equipment Do I Need?

All you need is some string, pegs and a sprayer. You can either use a small sprayer with a capacity of about 1 gallon or 5 litres, or alternatively use a knapsack sprayer which you carry on your back. These hold about 16 to 22 litres of mix and although need refilling less frequently, are more cumbersome to use and weighty for those of you of slight build, and not used to carrying heavy loads on your back. Remember 20 litres of water weighs 20 kilos or 44 pounds. You can of course leave a knapsack sprayer on the ground during use and partially fill it, but it will have to be constantly moved around.

A small capacity sprayer like this one is very useful
A small capacity sprayer like this one is very useful | Source
Knapsack sprayer
Knapsack sprayer | Source

How to Get Rid of Moss in Lawns

  1. Mark out the lawn in strips
  2. Mix up the iron sulphate solution. Use 3 heaped teaspoons per litre
  3. Spray along the strips, while walking, moving the sprayhead backwards and forwards like a windscreen wiper

Step 1 - Mark Your Lawn

The idea is to spray the lawn in strips so that you know where you have covered. I use 2 pieces of string wrapped onto scrap metal rods or rebar. You can also use canes or pieces of tree branch. Start off by marking out a strip about a yard wide. When you complete spraying the first strip, you simply move the strings.

Use, string to mark out the lawn
Use, string to mark out the lawn | Source
Mark out a strip about a yard wide
Mark out a strip about a yard wide | Source

Step 2 - Mix The Solution

To prevent lumpiness, add the iron sulphate to the sprayer first. Next add the equivalent of a few cups of warm water and swirl the mixture until it dissolves. Finally top up with warm but not boiling water (which could potentially damage the sprayer). Tighten the lid on the sprayer and turn it upside down a few times and give it a shake to ensure thorough mixing. If you are using a knapsack sprayer, add water about a gallon at a time, and swirl the mixture around each time you add water.

Mixing Iron Sulphate and Water - What Concentration Do I Use?

I did some surfing online, but there didn't seem to be any any consistency as regards mixing concentration. So I decided to do some some experiments.

This is the concentration which seems to provide good results:

3 heaped teaspoons per litre


I worked out the weight of a heaped teaspoon and it's about 7 grams

So 3 teaspoons equates to 3 x 7 = 21 grams per litre (liter)

For those of you living in the USA, this is equivalent to 2.8 ounces per US gallon

The Imperial measurements equivalent is 3.4 ounces per UK gallon.

You can double up on the concentration to ensure more thorough results, but I have found this to be unnecessary. It also tends to blacken the grass as well as the moss (not so much an issue when grass is growing vigorously as this discoloration will disappear after a few cuts). It also tends to stain concrete and gravel driveways.

Instead of using teaspoons which can be tedious, you can use an old weighing scales for weighing out the iron sulphate. Alternatively use a disposable cup or other container and add the required number of spoons into this for the capacity of your sprayer, e.g 5 litres. Mark the inside or outside of the container. Then in future you can just measure out by volume rather than by weight.


So to summarize:

Approximate Equivalent Mixing Concentrations

Measurement Units
Concentration
Metric
21 grams per litre (3 heaped teaspoons)
Imperial (Sometimes still used in UK)
3.4 ounces per Imperial Gallon (14 heaped teaspoons)
US Customary Units (USA)
2.8 ounces per US Gallon (11 heaped teaspoons)
Mixing concentration in heaped teaspoons

Units Conversions

1 ounce = 28.35 grams

1 US gallon = 3.79 litres

1 UK imperial gallon = 4.54 litres

Source

Step 3 - Pump and Spray

  • Its probably a good idea to wear goggles in case the spray gets in your eyes. Try to spray on a windless day
  • If you are using a small 5 litre or gallon sprayer, pump it the recommended number of times or until the safety valve operates. For a knapsack sprayer, you just need to operate the handle a few times, and re-pump as spray pressure starts to reduce
  • Spray within the strip you marked out, moving the spray head left to right like a windscreen wiper, and walking either backwards or forwards along the strip
  • When you reach the end of the strip, move one of the lines to create a new strip, adjacent to the one you just sprayed. Continue this "leap frogging" process, moving each line in turn until you have sprayed the entire lawn surface
  • Within about 20 minutes, moss turns black. Spray any spots you missed
  • After about a month and when the moss is completely dead, pick a dry day and rake it out.

Source
Moss turns black after application
Moss turns black after application | Source

Killing Moss on Driveway

You can use iron sulphate on a driveway, but it does have a tendency to stain, and this is more noticeable on gravel or concrete. You could spray a patch in a area that isn't prominent first, and see how it turns out. An alternative is to use a solution of bleach and water. Always use eye protection when spraying bleach solution.

Will Moss Grow Back?

It usually will, however treatment with iron sulphate in winter or spring suppresses it for the summer, until the weather gets colder and wetter in the autumn and it begins to grow again. Grass becomes dormant during winter and without this competition, moss will thrive unless treated.

Questions & Answers

  • Does moss ever die in dry weather, or can it stay dormant when dried out for months?

    Some moss species may die or produce spores so that new plants will develop once rain arrives. Generally, though, moss can become dormant and will re-sprout once weather becomes wetter.

  • We are planning to remove some point trees in our side yard which is full of moss. Will opening up the space to sunshine prevent the growth of moss?

    It may help, because lack of sunshine can reduce the rate at which ground dries out and also moss seems to need less sunshine than grass to thrive. However, it's not guaranteed that you'll have less moss. My lawn is full of moss after a long, cold wet winter, even though it's in full sun. Feeding a lawn so that grass grows strong and competes with the moss will help. Also forking the ground by hand or with a special machine will improve drainage so that the ground isn't so sodden all the time. The application of iron sulfate does help, and although it doesn't kill moss completely, it suppresses it for the summer.

  • I bought fine powder ferrous sulfate. I assume that it's the same, and that I can use it in a 25-gallon electric pump sprayer like the one on the back of a four-wheeler. Do I spray when it's sunny out with rain in the near forecast, or does it matter?

    I usually spray when it's sunny or overcast, and not windy. It's probably not a good idea to spray when rain is imminent to allow a few hours for the solution to be absorbed by the moss.

  • Where can I buy iron sulfate?

    It's widely available from home stores, gardening shops and the gardening section in supermarkets. You can also buy it online from Amazon. It's available in various sized bags from 2 to 50 pounds. The link below is for 10 pounds.

    https://www.amazon.com/gp/product/B00KJLAJXS/?tag=...

© 2015 Eugene Brennan

Comments

    0 of 8192 characters used
    Post Comment

    • eugbug profile imageAUTHOR

      Eugene Brennan 

      6 months ago from Ireland

      I don't think it matters, but possibly when the moss is dry, it'll absorb more solution than when it's wet.

      Don't spray when rain is imminent because it'll just get washed off.

    • profile image

      scollings@telus.net 

      6 months ago

      We live in a very wet climate and I use a spreader to cover the lawn with ferrous-sulphate, is it best to spray with the lawn wet or dry or does it matter?

    • eugbug profile imageAUTHOR

      Eugene Brennan 

      3 years ago from Ireland

      Thank you all for the kind comments!

    • Writer Fox profile image

      Writer Fox 

      3 years ago from the wadi near the little river

      You provide excellent instructions and wonderful graphics to explain how to kill moss in a lawn. I agree with you that it is best to prevent it from growing in the first place. Enjoyed and voted up!

    • Shane Ilagan profile image

      Shane M. Ilagan 

      3 years ago from Philippines

      Very informative article! Thank you for sharing!

    • Amanda6868 profile image

      Amanda M 

      3 years ago from Unknown

      Very useful! Voted up!

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, dengarden.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://dengarden.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)