Written by Terry Smith

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UK’s best moss killer rated for effectiveness on driveways, block paving, lawns, tarmac, and roofs

This article was last updated on April 23rd, 2022 at 6:11 am

We’ve all had a moss problem in our home at some point. It could be the lawn, decking, the roof, driveway, brick wall or in between block paving. Moss can actually be quite slippery and therefore dangerous, let alone ugly and unsightly when growth occurs in unwanted spaces. Pinning down a single cause of moss is very difficult – my personal opinion is a combination of wind, birds, and insects carry these tiny spores but some would say almost impossible as there are a lot of factors at play.

Moss six months after still gone and roof looking tip top

So what can be done about this problem? Actually, quite a lot. The UK market is flooded with products designed to tackle moss, whether it is on a hard surface like a garden path or driveway, or on a lawn. However, sometimes moss killer isn’t the direct answer, it could be an Algae remover is better, there are also other alternatives that don’t involve chemicals so please feel free to take a look at where moss appears and how to kill it as well as what you need to know when buying moss killer.

Best moss killer: SmartSeal Moss Killer – personally tested on a delicate roof to incredible effect – see my roof
Alternative if SmartSeal unavailable: Simply Spray & Walk Away
Best budget: Patio Magic Patio Cleaner 5L
Commercial pick: SmartSeal Moss Killer
Best moss killer for lawns: head over to lawn weed and feed

Not all products are as effective as they should be though, and we thought it would be helpful to take the best sellers and test/review them for you to find the best moss killer available in the UK and taken a list of 15 and cut them down to 5 relevant moss killers that meet our quality gudelines. A moss killer should work effectively in a reasonable time frame, be well priced, biodegradable, safe for use with children or pets, and easy to apply. We have reviewed products that can be used on patios, block paving, wood, and any hard surfaces in general specific so that we are sure you’ll find something that will help you out with your own moss problem.

What you need to know when buying the best moss killer

This short moss killer buyer’s guide will give you all the information you need to know – by the time you’ve read my article you’ll either no longer need moss killer or know exactly which one you need.

Granules, concentrate, or ready to use?

On the other hand, if your problem is on your patio stones or garden path, you are probably going to be better off using a liquid form of moss killer like the SmartSeal. These usually come in concentrate form and need to be diluted with water before use, but there are some that come pre-mixed and ready to use. Concentrates offer you more control over the strength of the solution but they do require a little more preparation. Ready to use products are more convenient but you are stuck with the solution as is.

When to apply moss killer?

Concentrates work best when they are applied to a dry surface and are allowed to dry in for a few days. If you experience heavy rain within 48 hours of you spraying, it might have a negative effect on the performance of the moss killer so have a keen eye on the weather. Granules work differently and the optimum time to use them is in spring when the temperature rises above 10 degrees Celsius and there are frequent rain showers – you’re essentially waiting for rain to activate them but I prefer the liquid as it’s more controllable and fills me with more confidence around pets and kids.

Be patient

Moss killers take time to work, so please be patient. Granules that are used on lawns are particularly slow acting, and this causes some people to add more, thinking that they aren’t working. This actually causes damage to the grass and makes the problem worse.
Concentrates work faster so you should see the difference within 3-7 days in most cases.

Be careful and follow the instructions

If you are spraying concentrate on an area that is in close proximity to your plants, you have to be very careful or you might kill them. It might be a good idea to temporarily cover them with something while you spray just in case. Also, make sure that the area is fully dried out before letting any pets or kids play in there as there will still be toxins around if it is still damp. Remember to always wear gloves when working with any chemicals and don’t enter the house with the same shoes that you were wearing while applying the moss killer or you could damage your floors or carpets.

If you follow our advice set out here in this buyer’s guide, and choose one of the excellent products we have tested and reviewed for you, we are sure that any problems that you have with moss or algae will soon be a thing of the past. If you are looking for a good pressure sprayer to apply a moss killer concentrate we have a page full of reviews of such products so why not pop over and take a look?

Still feeling a little lost about what product to buy and how to use it for best results? Checkout the where moss appears further reading below:

Where moss appears and how to kill it

Moss can take hold in a considerable number of places including driveways, block paving, lawns, tarmac, artificial grass, gutters, and roofs. Moss killer isn’t always the best solution so let’s look at where and how to deal with it:


Starting with lawns, you can use a lawn scarifier and then move onto a lawn weed and feed. The moss that grows on your lawn is a separate problem entirely and requiring a different type of product to get rid of and help your grass grow back to its previously healthy state. Moss growing on your lawn could be caused by any number of things but most likely spores were carried by wind and insects and it could well be your dried out. The drought causes the grass to thin and moss can take over and not crowded out, but if you over do it with the hosepipe and cause your lawn to be waterlogged, guess what? Yes, that’s right. Moss growth. Again it really comes down to the grass being too thin.

When moss starts taking over lawns it doesn’t stop

It could also be caused with problems in the soil such as it being overly acidic – a soil tester is the best bet if you have any inkling that’s the issue. If your Honeysuckle, Lavender, Lilac, or perhaps Spindle or Lily of Valley are struggling that would be a sign of acidic soil without a test.

Driveways, pathways, patio, block paving, and tarmac (stone/porous solid surface)

Before you go and throw down a load of moss killer granules, let’s take a step back and look at this. The absolute best way to clean block paving and driveways is with a petrol pressure washer and some cleaning detergent.

Before cleaning steps
After patio cleaner and a petrol pressure washer

The only reason not to get your hands dirty is you’re worried about damaging the surface – always do a test patch first. In the event you don’t like what you see then move onto a more gentle moss killer. However, once you clean up any concrete/porous surface, that’s only half the job done. You need to use patio sealer.


Again roofs can be handled with a pressure washer but it’s not the easiest. If you take a look at this article I stripped all the ivy and moss off the roof. I used SmartSeal for this as it was a very very precarious setup of Kent peg tiles. The moss went brown after a day and a week later was literally falling off.

It was a bit weird though – the moss at the bottom browned much quicker – I can only assume more moisture up top somehow? Or I simply didn’t apply enough which is far more likely. Anyway, without destroying the roof I managed to clean it up and reasonably in part thanks to SmartSeal:

As you can see there are some remnants – I watered it again with a one to five – this picture is about six months on after I gave it the last dose. The house has changed a bit since with nice cladding as well:

Moss six months after still gone and roof looking tip top

So as you can see for delicate jobs I can’t recommend it enough. It clearly has the power to kill moss without damaging hard but brittle surfaces – nor discolour them from what I can tell. I probably did more damage putting the flue in for central heating – how a home can go that long without blows my noodle 😀 And, I know it’s so good you’re thinking is this really legit? Check the little window – completely restored all except that little pantry window – still need to paint that!


Funnily enough I learned the hard way with the cladding about moss and algae – this starts to build up too on the wall that stays damp longer and doesn’t get the sunlight – I did that because of the pebble dash and not wanting to paint and maintain it! There’s no such thing as maintenance free, but a mist of moss killer in the dry seems to be working to keep that at bay, for the moment at least, I’ll update that next time I update this article.

SmartSeal make arguably the best patio sealers in the UK so why would their moss killer be any different? Well, it’s not, it’s the best moss killer in the UK without question and is what the commercial guys are using. You’ll see result in a couple of days – when I did my roof that’s what happened for me and the results for 6 months after were fantastic. The thing to watch for is the moss starting to turn brown – that happened after about a day for me but it was bone dry – perfect conditions.

Image credit: Smartseal Moss Killer – what you can expect from a one to three mix

It’s suitable for hard surfaces such as decking, driveways, patios, tarmac, and roofs. Application is a doddle – if it’s mild moss coverage like you start to get in between paving stones or the beginnings on tarmac driveways then a one to five solution is jus the ticket. Another scenario is your paving stones are starting to discolour. Mix it up with a watering can and lay it on – it’s non toxic so no need to worry too much. This example wants a one to five mix and you can cover about 100m2, maybe a bit more with 5 litres:

Moss starting to build up on patio slabs and wants a one to five mix

If you’ve got thicker coverage like the before and afters above then you’re probably going to want to go with one to three.

After you’ve cleaned up and it’s all dry, you can coat again as a preventative measure and don’t need to worry about the kids and dogs. Just let it dry again of course – it’s biodegradable and so once dry not active.

The best bit though since it’s commercial grade – there’s massive discounts for bulk. Five litres works out to be about £18 quid – an absolute steal for the quality – if you buy in bulk it’s the budget pick as well! Easy to see why this has fast become a best seller since I updated the review 18 months ago.

If your moss problem is on your driveway, fence, or just about any other hard surface, Pro-kleen’s simply spray &walk away moss killer should be right at the top of your shopping list. It is easy to mix, all you do is use one part concentrate to four parts water and you’re good to go. Then use any garden sprayer to apply it to the moss infected surface and wait for it to start working. Just like the name says ‘simply spray & walk away”.

We tested this on some old wooden garden furniture whose legs had been colonised by green moss recently while it was stored in a shaded corner of a garden. For the first couple of days, there wasn’t any visible change and I was ready to write it off as an overrated product, but then on the third day we started to see something, and it just got better and better, day by day, until the moss was completely gone. We also tested it on some wooden fencing and this time the results were obvious on the second day. I have to say I was impressed.

There is a knack to getting the most out of products like this and it all comes down to timing when you apply it to the infected area. For more details please read our buyer’s guide at the bottom of this page.

Usually, the moss and weed killing products that work the best are quite strongly bleach based, but this is non bleach, non-caustic, non-acidic, and is completely biodegradable with a neutral PH balance. You’ll have to keep your kids and the dog away from the sprayed area for a little while, but once it’s dried they are safe to play around there.

A five litre bottle of this moss killer concentrate costs around 15 pounds, and once mixed with water will give you five times that. What’s more you don’t have to worry about using it all before the expiry date as there isn’t one. You can have this sat in your shed or garage for as long as you like, ready to use again.

Pro-kleen have come up trumps here with this fantastic moss and algae killer and I have no reservations about recommending it to anyone who has a moss problem on their path, decking, fencing, etc. A must buy.

Not interested in products that you have to mix and measure? Don’t own a garden sprayer?

With the Patio Magic ready to use spray, everything is already set up for you, leaving the only task of actually spraying the moss killer onto the affected surface. This solution comes pre-mixed so there’s no measuring to worry about, and attached onto the 5 litre bottle is a small, battery operated sprayer (four Duracell AA batteries are included). This really is a handy product for people on the go who don’t have time, or just simply don’t want to spend time, going through the whole process of measuring, mixing, pouring into a sprayer, etc.

A 5 litre bottle of this ready to spray moss killer will set you back around 20 pounds and will allow you to treat an area of about 35 square metres. There is a concentrate version of the same moss killer available which costs about 4 pounds less, but there is no sprayer included and you will have to go through the mixing process yourself.

So, does it work?

The answer is definitely yes. I’m always wary of products that offer things like free sprayers and such as they are often gimmicks used to hide an inferior product. Not so, in this case. We sprayed an area of patio that has some moss and lichens, but unfortunately a rain storm came out of nowhere and soaked the sprayed area= so we had to wait and try again when it was dry. This time though we got luckier with the weather, and saw that the moss killer was indeed doing its job after a couple of days.

Like the simple spray & walk away moss killer, your kids and pets are free to play in the sprayed area once it has completely dried. However, this product can be harmful to your plants so be careful when spraying.

This is a moss killer that offers a ready to go, easy to use product to those who desire that kind of thing and it works well if used correctly. At its current price point it isn’t as cost effective as buying a concentrate but I guess that’s the cost of convenience.

If you’re using this to sort out the patio, I highly recommend sealing afterwards, so take a look for a good patio sealer here to complete the job and a full guide on restoring your patio.

4. Wet & Forget - Moss Mould Lichen & Algae Remover (5 Litre)

Wet & Forget claims to be a tried and tested product and used by theme parks and other public places to kill moss and keep it away from various hard surfaces. Well, not one for believing in advertising spiel, I decided to put it to the test on some concrete steps to see for myself if it lived up to the company’s claims.

This moss killer comes as a concentrate in a 5 litre bottle for around 30 pounds in the UK. The recommended dilution is one part concentrate to one part water, and after a little bit of calculation I worked out that a five litre bottle should cover an area of about 200 square metres or so.

After mixing the moss killer and spraying the steps, we waited to see results. Knowing that patience is key with these products we weren’t surprised to see nothing had really happened after a day, then two, then three, but after day four we were ready to condemn Wet & Forget.

Then it happened, on day six the moss began to die, and die quickly. That was over 2 weeks ago and I’m happy to say that all the moss has gone and there are no signs of it coming back any time soon, fingers crossed. This stuff really works, it just takes a while longer than most so be patient.

The makers claim that once it has dried into a surface, it will continue to work on killing moss and will be reactivated every time it rains in the future. I can’t attest to that to be true as it hasn’t been long enough since we sprayed it to say, but after looking online at customer feedback, it seems that it is true.

This moss killer matches the simple spray & walk away product in safety design as it too is non-caustic, non bleach, neutrally PH balanced, biodegradable, and safe for your family.

All in all, a great moss killer for steps, patio, block paving etc. at a reasonable price. Just expect to wait a while to see results.

If you’re looking for a moss killer that works on patios and the like, you are spoilt for choice these days. Jarder’s spray & leave is yet another fantastic product for just such a problem and very fairly priced too.

This super concentrate’s recommended dilution is one part moss killer to 5 parts water, but Jarder says this is only a general guideline and you are free to add more or less water depending on the severity of the moss problem.

We stuck with the maker’s advice for our test and chose a particularly mossy bit of decking as our ‘canvas’. Using a pressure sprayer, we put a decent coat of the soapy like substance on half of the decking so that we could check back in a few days to see how it compared to the untreated half.

Jarder claims results in 2-3 days and for it to keep on fighting moss for 6 months after. I can’t comment on the 6 months part of the claims, but after three days there was a noticeable difference between the two different parts of our test area. A couple of days after that and it was even more clear which side had been treated with the spray & leave moss killer.

It was also blindingly obvious that we hadn’t been so careful while spraying too as a couple of nearby plants had copped a coating and were starting to wilt. Even though most of these products are biodegradable, non-bleach, etc. these days, they are still not good for your plants, so be a little more careful than we were when spraying.

Spray & leave can be used on almost any kind of hard surface from fencing, to roof tiles, and even PVC window frames, and does an excellent job of getting rid of moss and algae. This is another product I can wholeheartedly recommend.

Our aim is to take the guesswork out of buying gardening products so that every customer, is a happy customer

About Terry Smith

I’m Terry Smith from gardentoolbox.co.uk, a professional landscape designer, hobbyist gardener, and barbecue fanatic with 20 years experience building and restoring. So as you go through my site you'll watch me document some of the professional garden installs I make as well as the major projects I take on at home. While sharing those experiences and guiding you, I'll be recommending some great tools I use to enable this along the way so you can really buy in confidence. Always feel free to pop me a message: info@gardentoolbox.co.uk

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