The Best Moss Killer For Lawns

Written by Daniel Woodley. Reviewed by Elizabeth Smith. Published to Lawn Care on 2nd January 2020. Updated: 22nd February 2023.

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Lawn moss isn’t just unsightly, it can grow at an incredible rate, and I’ve seen it smother the ground preventing grass from establishing itself.

If you want that perfect green, lush lawn that so many gardeners in the UK dream of, you’ll need to kill any moss that currently exists and also take steps to stop it from returning.

I have experience with three of the most popular moss-killing products on sale in the UK. They all work differently, so let me show you what you can expect from these lawn moss killers:

These are the three products:

1. “No Rake” moss killer (Over 575 reviews on Amazon)
2. Iron sulphate (Over 2000 reviews on Amazon)
3. Miracle-Gro “All in One” (Over 19,000 reviews on Amazon)

Expert Tip:

The growth of lawn moss can be the result of five things, and before you buy a lawn moss treatment product, I suggest you try my quick tips:

• Too much shade – cut back branches from trees and shrubs; I’ve seen this make a big difference to the quality of the lawn.
• Drainage issues – if you have a large garden, consider a French drain or similar to divert water away from the lawn.
• Soil nutrient issues – add feeds and fertilisers so grass grows thick enough to block out the moss.
• Compact soil – try using a lawn aerator or plugger once a year.
• Close mowing – in shaded or damp gardens, I’ve found it’s better to cut and strim the grass higher rather than too close to the ground.

I’ve also published a more detailed guide to growing lawns in shaded gardens.

Below you’ll find three products that I have experience using:

Product 1) “No Rake” Organic Lawn Moss Killer

Viano’s MO Bacter is my favourite lawn moss killer and for good reason; it’s one of only a handful of moss treatment products where you don’t need to rake out the dead moss after applying the product.

This lawn moss killer contains two key ingredients, a moss killer and also a naturally occurring bacteria that consumes the dead moss and thatch that collects at the base of the lawn.

All “No Rake” lawn moss killers work slowly, gradually killing off and consuming the moss. This gives the existing grass time to spread into the free space. 

I also overseeded at the same time and the seed germinated just as the moss was breaking down and decaying.

This product is so reliable that a company I advised was chosen by the War Graves Commission to treat and remove lawn moss from their graveyards. The commission was concerned about potential damage to the headstones from more aggressive moss treatment products (iron sulphate).

I only have one issue with “no rake” lawn moss products; I found they are slow to act and when I tested them and I had to apply several doses and overseed a couple of times.

“No Rake” is my favourite lawn moss killer, but it’s not for everyone.

What I Dislike

• Slow to act
• Requires several applications
• I had to overseed twice so the new grass would fill the void

My Experience With “No Rake” Moss Products

15 years ago I treated a nasty moss infestation on a lawn with harsh chemicals (iron sulphate) that left the lawn black and unnattractve.

Fast forward a few years and I found myself with another mossy lawn, so I tried another method – the no rake option.

I discovered that:

• It took a couple of applications and around 6 weeks for the bacteria to completely eat away the moss.
• I overseeded twice and some germinated at the first attempt while others at the second.
• The lawn never went black.
• It did look a bit patchy for a while as there was some overlap between the bacteria getting rid of the moss and the seeds germinating.
• I found that keeping the lawn moist helped, so on dry days I would water it lightly in the evening.

Product 2) Iron Sulphate

Iron sulphate is one of the most widely used products for the eradication and control of lawn moss.

It’s cheap and you can get hundreds of litres of diluted product from just one kilogram of powder, and I know from experience that it’s incredibly effective.

When I last used this product, it blackened the moss in a matter of days.

I found that applying it was easy, I just diluted the powder in my watering can and applied it evenly to the lawn.

While iron sulphate was very effective at killing the moss in the lawn, it’s not my favourite product for one simple reason – the damage it can cause to patio slabs, concrete, carpets and decking is severe and often irreversible.

Iron sulphate eats into patio slabs, marble and concrete, leaving permanent marks. It also damages timber decking, which must be sanded and recoated.

Even transfer from pets, wild animals, and shoe soles can wreck patios and flooring.

Iron sulphate also harms pets and children, who must be kept off the grass for at least 24 hours.

Apply too much iron sulphate, and your grass may turn brown or even black, although from what I’ve seen, it usually recovers within a month or two.

Please note: Due to regulations in the UK, iron sulphate marketed to control plantlife must be approved by the relevant government agency. Iron sulphate that is sold as a lawn greener or tonic is not subject to the same regulations, hence why you may see iron sulphate marketed differently. If you’re in doubt, choose a product labelled “iron sulphate moss killer” as it should come with instructions and safety advice.

What I Dislike

• The moss went a dark brown/black colour and looked awful.
• Iron sulphate will damage some patio slabs, concrete and carpets should it come into contact with them.
• It’s not safe for pets or children who should be kept off the lawn when it’s wet.
• I still had to rake out the moss, or live with a black lawn for months.

My Experience With Iron Sulphate 

I used to work for a landscaping firm years ago, and they always insisted on using iron sulphate to kill off lawn moss and greenup the grass.

While it certainly worked, these days in my own garden, I prefer to use the “no rake” lawn moss killer as it doesn’t blacken the moss, and I can overseed immediately. I’ve found this approach is easier and more effective.

Based on my experience with “no rake” products, I think you’ll get better results using them when the lawn is actively growing, not in winter or during heatwaves when the grass is dormant.

Product 3) Miracle-Gro “All in One”

All-in-one products like this one from Miracle-Gro are billed as the perfect solution for gardeners – they contain a bit of everything; nutrients for health, two weed killer chemicals and also some sulphate to kill moss.

Unfortunately, I’ve tested and researched this product and I don’t believe the moss chemical doses are high enough to eradicate a nasty moss infestation.

Based on my experience, I can only recommend this and other “all in one” products to those that have a great lawn and are looking for a cheap maintenance/preventative product that has a bit of everything in it.

If you have serious moss issues in your lawn, I suggest buying a dedicated moss killer to get rid of it; you could then use an “all in one” product to stop it from coming back.

My advice also applies to weeds, I’ve seen first-hand how Miracle-Gro failed to kill off a nasty weed infestation in a lawn, but it’s great at preventing weeds from taking hold in the first place.

What I Dislike

• It’s not a dedicated moss killer.
• It works best as a deterrent and preventative measure.

How to Stop Lawn Moss Growing Back

Moss grows in lawns for several reasons, but from what I’ve seen, it usually thrives in north-facing and damp gardens.

The good news is you can rid of it and grow a healthy, lush lawn.

Have a look at the photo below, this was once a shaded garden with very little light penetration. By cutting back the branches, using a decent moss killer and tending to the lawn properly, I managed to get it to an acceptable condition:

Is it perfect?

No, but considering there are three pine trees at the end of the garden and half the lawn *never* gets any sunlight, I’d say it’s not bad at all, and it’s moss free.

Read my guide to growing a healthy lawn in a shaded garden.

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