What is Lawn Sand? How & When to Apply it for Best Results

By   | Last Updated :   July 18, 2022 | Filed In :   DIY & How To

Moss on your lawn? Some weeds, too? Lawn sand could help you control them while also acting as a grass feed that makes your lawn greener.

While not as popular as it once was, lawn sand still has its uses. Plus, it’s easy to find, affordable and you can apply it by hand.

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Lawn sand is a moss and weed killer and controller as well as a grass fertiliser. Although in recent times it’s often substituted with more potent and specialised products, it remains useful if you want to deal with common lawn problems without herbicides and pesticides. But to see results, you need to apply it regularly without overusing it.

Read on to find out what lawn sand is and how to use it properly.

What is lawn sand?

Lawn sand is made of sand, ammonium sulphate, and iron sulphate (also known as ferrous sulphate). The ratio of these ingredients varies depending on the manufacturer. Despite the name “lawn sand,” the key ingredients in the mix are ferrous sulphate, a moss and weed killer, and ammonium sulphate, a nitrogen fertiliser.

Let’s take a closer look at what each of these ingredients does.

Lawn sand can be micronised or coarser, depending on the brand and quality of the product. Next, let’s review its main uses.

What is lawn sand used for?

You can use lawn sand as a general feed for your lawn, to kill moss and weeds, and to improve drainage. It can also help to acidify the soil and push earthworms deeper into the ground.

1. General feed

Lawn sand is a nitrogen fertiliser that makes grass look greener. It also promotes the growth of grass. Because of this, it’s a good general feed for your lawn. But bear in mind that applying too much lawn sand may damage the grass.

lawn revived by lawn sand

A lawn revived by applying lawn sand. Image credit: @foxlandscapes

2. Moss control

Lawn sand is a traditional way to scorch moss that competes with the grass for your lawn. Unlike specialised lawn products for killing moss, it includes no herbicides or pesticides. Lawn sand is an environmentally friendly option and it’s safe for children, pets, and any wildlife that may visit your garden.

3. Weed killer

Lawn sand can also kill weeds with wide leaves. Broadleaf weeds include dandelions, clover, daisies, and buttercups. We’ll talk more about how this happens in a bit. When applied regularly, lawn sand can also prevent weeds from growing while promoting the healthy growth of grass.

4. Drainage improver

Another benefit of lawn sand is that it can help to improve soil drainage. While not a replacement for scarification, slitting or spiking, it can prevent waterlogging and lawn diseases.

5. Soil acidifier

Over time, lawn sand can change the pH level of your soil to make it more acidic. You may want this if you are growing fescues, bents, and other fine lawn grasses. However, if your soil is already acidic, consider checking the acidity level before applying a lawn sand treatment.

6. Reduced earthworm activity

Lawn sand helps to deal with earthworms in two ways. First, earthworms don’t thrive in acidic soil, and as we’ve seen, lawn sand improves soil acidity. It will also make the soil more abrasive and reduce its moisture content. This will discourage earthworms from dwelling within the upper layer of the soil.

How does lawn sand kill moss and weeds?

Lawn sand starts to kill moss within 7 days. It works as a selective killer of moss and weeds because it comes as a fine powder that covers them without sticking to the narrower blades of grass. The grass continues to breathe and, with the dose of nitrogen fertiliser it gets, should become greener within as quickly as 2 weeks.

The blades of grass may turn a black colour before dying off. Depending on how much moss there is on your lawn, you may end up with gaps that you need to fix.

While lawn sand helps to control moss and weeds, it’s not a targeted killer of either. If you’re dealing with a weed or moss infestation, dedicated moss and weed killers are more effective.

It’s important to understand that lawn sand isn’t a magical moss and weed killer. You have to apply it regularly and give it time to see results.

When you shouldn’t use lawn sand

While lawn sand has its advantages, it’s not the best solution for a major moss or weed outbreak. For extensive weed and moss lawn problems, you can find dedicated products that are less damaging to the grass. Also, you shouldn’t count on lawn sand as a quick fix for lawn problems. It may scorch patches of the lawn, which will need a few weeks to recover.

Nor should you use lawn sand as a top dressing or lawn leveller. It may cause soil compaction without adding any nutrients to the soil. Compost is a better top dressing for a lawn as it’s rich in nutrients.

You may use sand as topsoil, but only in combination with clay and silt. It also depends on the type of soil you have.

Lastly, keep in mind that lawn sand isn’t just sand. It contains iron sulphate and ammonium sulphate, which will fertilise the soil and increase its acidity. If the soil is already acidic or has been fertilised, you may not want to apply lawn sand to it.

When to apply lawn sand

The best time to apply lawn sand is early in spring, after the soil begins to warm up. Pay attention to the first signs of new growth in your lawn. In the UK, this can be as early as the middle of March. The ideal time to apply lawn sand in spring is in between cuts. Wait at least 3 days before and after cuts.

Applying lawn sand too early may damage the grass. The iron sulphate will kill the moss but the ammonium sulphate won’t work to fertilise the grass if the soil is still cold.

You can continue to apply lawn sand throughout summer and up until early autumn. Lawn sand works best if you apply it every 4 to 6 weeks.

You shouldn’t apply lawn sand in winter or during freezing conditions. It will be ineffective. Instead of helping the grass, it will only damage it.

Warning: Don’t use lawn sand during a dry spell. It may scorch the grass. You may also want to avoid applying it during windy weather as it may be carried beyond the lawn and stain any surface it comes into contact with.

How to use lawn sand: The best way to spread it

You can spread lawn sand by hand or using a spreader. Both methods are effective, but using a spreader will help you to cover a large area more easily. Whether you apply lawn sand by hand or manually, avoid applying too much or you may hurt the grass. More is not better!

lawn sand spreader

Apply lawn sand with a spreader for best results. Image credit: @artbyrlwebsterlajmi

How much lawn sand do I need?

You need between 80 grams and 150 grams of lawn sand per square metre. The exact quantity you should use varies from product to product. Check the instructions on the package for the optimal dosage and don’t forget to calculate the total area of your lawn.

Remember that to see results, you have to apply lawn sand repeatedly. You may want to buy enough for several applications. Since the ratio of ingredients can vary from product to product, use the same brand for consistent results.

How to apply lawn sand by hand

To apply lawn sand by hand properly, it helps to divide your lawn into squares using bamboo canes or strings and pegs. Use a measure such as a plastic cup to apply the right amount of lawn sand to each square metre. Make sure to use gloves and to rinse your hands thoroughly after.

How to use a spreader

Applying lawn sand with a spreader is convenient. Most spreaders will allow you to control the amount of seed that gets spread. For best results, divide the lawn sand into two equal parts.

Put one part into the spreader and move from north to south. Then put the second part in and go east to west. Covering the lawn twice like this ensures the even application of lawn sand while minimising over-application.

Be especially careful when using a spreader as the wrong setting or overlapping when turning may make you apply too much lawn sand.

Tips for putting sand on your lawn

Mowing at the right time, watering, and scarifying the lawn is important when applying lawn sand. Do them in the right order for a healthy lawn.

  1. Mow the lawn 3 days or so before you use lawn sand. Never mow a lawn right after spreading lawn sand over it!
  2. Water the lawn 48 to 72 hours after applying lawn sand unless it rains. If it rains in this interval, you can skip the watering.
  3. Scarify the lawn with a rake around 14 days after the lawn sand application to remove weeds and dead moss. If this leaves gaps in the lawn, you may have to overseed.
  4. Don’t put lawn sand on a newly seeded lawn. Allow it to become established for at least a year.
  5. Repeat the lawn sand application every 4 to 6 weeks to control weeds and moss and fertilise the grass.
  6. Rinse any tools that come into contact with the lawn sand with water as the iron content in it may stain them.

Lawn sand alternatives

You can find many alternatives to lawn sand in the form of all-in-one or specialised products available as granules, powders, or liquids. Here are some of your options:


Why put sand on grass?

Lawn sand helps to kill moss and prevent weeds, provides nitrogen fertilisation to the grass, and helps with drainage. It’s a traditional solution to some of the most common lawn problems you may be experiencing.

Will sand kill grass?

The iron sulphate in lawn sand may damage the grass, but the ammonium sulphate will help it recover. Don’t apply too much lawn sand on the lawn or do it too often, or it may kill the grass.

How does sand help grass grow?

Lawn sand contains ammonium sulphate, a nitrogen-based fertiliser that promotes the growth of grass. It can also help grass indirectly, by killing moss and weeds that compete with it for space and nutrients.

The wrap up

Lawn sand is a moss killer and weed controller you can count on as long as the problem isn’t too serious. It’s easy to use and acts as a grass feed too. It can also improve drainage and push earthworms deeper into the soil.

But lawn sand isn’t the most potent weed or moss killer. Nor is it the strongest lawn fertiliser you can use. For more serious problems, you can find more powerful products.

Lastly, keep in mind that you have to apply lawn sand regularly to see results. Check out our full guide on how often to feed and weed a lawn.

What is lawn sand How & when to apply it for best results-min

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  1. Richard leslie Axby
    November 27, 2022 at 8:55 am

    I have weeds coming up through my paving slabs. Will Lawn Sand kill the weeds and fill the gaps ?

    • Mike L
      January 24, 2023 at 10:18 am

      Hi Richard,

      Lawn Sand is a product that contains iron sulfate and is used to control moss in lawns. It is not typically used to kill weeds in paving slabs. If you want to kill the weeds that are coming up through your paving slabs, you will need to use a weed killer specifically designed for use on hard surfaces, such as a glyphosate-based product. It is also important to note that Lawn Sand will not fill gaps in paving slabs. If you have gaps between your slabs, you may need to use a different product or method to fill them in.


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