Patios and decking give us a useful outdoor space for relaxing and socialising, but without a good patio cleaner it’s not always easy to keep them looking great. When cold wet weather rolls in for an extended period, it tends to hit them with a nice layer of green algae, while black mould spots, moss, mildew, plant debris and dirt can all make your decking look dreadful or your patio seem past its prime.
The good news is that it doesn’t take a lot to sort these problems out, whether you’ve got a fancy pressure washer or not. There are specialist fluids and detergents designed to get your patio or decking back to its best. In most cases, there’s no scrubbing or rinsing involved, and one treatment should keep you clear for around six months of the year. Some patio cleaners will also work on any areas of paving, pathways, driveways or outdoor furniture, so everything in your garden can look spick and span.
Some patio cleaners are detergents that you can use with a pressure washer, while others are concentrated fungicides, surface cleaners or anti-bacterial disinfectants you apply by hand.
With the pressure washer detergents, you simply follow the instructions and add the detergent through a spray lance or a feed on the washer itself. Your pressure washer manufacturer may recommend specific brands or types of detergents – most usually their own – and the manual may have advice on what to use and how to add it.See related Best pressure washer 2022: Give your car, patio or driveway the big spring clean it needsBest garden hose 2022: The best hosepipes, kits and reelsBest garden furniture 2022: The best dining sets, swing chairs, benches and loungersBest patio heater 2022: Keep yourself cosy with our pick of the warmest patio heaters available to buy
The majority of patio cleaners that you apply by hand need to be diluted, and the mix is either applied from a bucket or watering can then brushed over the surface, or sprayed on using a garden sprayer. This normally means one that works under pressure using a simple pump, and preferably with a high-capacity tank and a separate spray wand. One of these will set you back £10 to £30.
The key thing is to follow the instructions, as different cleaners work in different ways. Some work better if applied to a wet or dry surface, and may need rinsing off a few hours after application. Others use a ‘wet and forget’ approach, where you just apply the cleaner then leave it on to do its work.
Yes. For example, if you have natural stone patios with Indian sandstone or limestone paving, they’ll be vulnerable to the spread of black spot – a particular type of lichen that can be challenging to remove – and there are special detergents aimed at tackling this. Other detergents might be designed to remove moss or algae. If you’ve got a particular problem with one or the other, it makes sense to use a cleaner that’s been designed to tackle it.
Not usually. You’ll often have to wait a few hours before seeing any difference, and in many cases the effects will seem small at first, but the area will look much cleaner after a few days. Patience is key.
Yes, but both of them require a decent application of elbow grease. You can spray the entire surface with water using a garden hose sprayer, then dissolve 75ml of washing soda in a gallon of hot water and scrub the surface with a brush soaked in the solution, re-dipping as required. Alternatively, you can sprinkle powdered dishwashing detergent over the entire surface and scrub.
However, not all patio cleaners come packed with harmful chemicals. Some use organic compounds and are biodegradable, so they’ll do no long-term harm to your garden or the environment.
If you've already got a pressure washer, it might do the job without any detergent. All the same, a patio cleaning fluid may do more to get rid of stubborn mould or algae, and will also leave a preventative layer to slow future growth.
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Price: £17 | Buy now from Amazon
If you’ve forgotten what your patio used to look like because a slimy green mess has taken over, then you need to get your hands on a bottle of this stuff. You can use it on all outdoor hard surfaces, from decking to driveways to patios, with no need for a pressure washer or scrubbing. Once it’s dried, it is broken down naturally in the soil so it doesn’t harm the environment.
It’s not as concentrated as some, so five litres might not go as far as you think, but it gets rid of one of the main culprits of dirty patios exceptionally well. You’ll need to be patient, though – it can take up to four days to show the results.
Key specs – Quantity: 5 litres; Can you use it without a pressure washer: Yes
Price: £7 | Buy now from Amazon
Kärcher makes some of the best pressure washers around, so it should come as no surprise that its patio detergents are top quality too. This one claims to have an active dirt remover; protection against wind and weather; and general protection to keep your patio looking good for longer. You can use it on all stonework – so that includes walls as well as patios – as well as aluminium, which means you can give the car a quick clean at the same time.
We tried it with the Kärcher K5 Premium Control (a hard-to-fault top-end pressure washer) and Kärcher K2 Compact (cheaper but still brilliant for everyday jobs) and although it guzzled up the litre of liquid very quickly, the speed and efficiency with which it cleaned is astonishing. Plus, you get lots of foam – very reassuring. But it’s expensive and you’re only supposed to use it with Karcher machines.
Key specs: Quantity: 1 litre; Can you use it without a pressure washer: No
Price: £37 | Buy now from Amazon
Black spots are those nasty black marks that can colonise on stonework after around three years. They start off tiny, at which point they’re known as black lichen, but they grow – especially on natural stonework – and can eventually cover it completely.
They’re a nightmare to clean, although not with this stuff to hand. You simply dilute it with equal parts water, apply to wet surface, leave it for at least an hour (keeping it wet) then wash away with a hose or pressure washer. That said, you might need a little scrubbing in really stubborn areas. You don’t need to worry about it harming natural stone and it slows down regrowth. It’s pricey, though.
Key specs - Quantity: 5 litres (25 litres also available for £90); Can you use it without a pressure washer: Yes
Price: £13 | Buy now from Amazon
This ultra-concentrated detergent is great for all kinds of jobs, cleaning not only patios and driveways but outdoor drains, greenhouses, plant pots and tools. A great all-rounder, it also disinfects and stops the patio surface being slippery. We found it worked quickly on moss and mould and left a really clean look, as well as making it smell nice.
We tried it in the bins and on a conservatory too and again: great results. It works well when applied by hand, but it’s also very effective when used with a pressure washer – often more so than the manufacturer’s detergent.
Key specs – Quantity: 1 litre; Can you use it without a pressure washer: Yes
Price: £11 | Buy now from Robert Dyas
This gave our patio testing area a good clean. Even the slimiest of algae comes off easily and you can use it on decking, fencing, paths, patios and driveways. It’s a preventative formula so it should slow down regrowth in the future and it’s easy to use as you mix it with water, pour it on and leave it to do its work.
You can wash it off with a hose or jet wash, the latter of which gave us better results. It does have its limitations as exceptionally dirty patios will probably need something more powerful – or at the very least a jet wash both before and after use of the product.
Key specs – Quantity: 4 litres; Can you use it without a pressure washer: Yes (up to a point)
Price: £29 | Buy now from Amazon
For instructions, the clue is in the name. You just mix one part concentrate to five parts water in a garden sprayer, then give your decking or patio a good soaking. Once that’s done, you can leave it a few days and see what happens. It’s a lot less effort than using a pressure washer or scrubbing with a brush, and there’s no bleach or acid involved. In fact, the formula has a pH value that’s just above water, although the manufacturers warn that it can be toxic to aquatic life. Once applied, it’ll clean and protect your wood or stonework for a year or more.
You do need a little patience with this one. While the effect varies, you might find that, for the first day or two, nothing much seems to have changed. However, as time goes on all that slippery algae and stubborn mould will disappear, and the longer you leave it, the better it gets – especially if you have some rain. And while it seems expensive for what it is, the 5L of concentrate makes 30L of spray, so you won’t need any more for a while unless you’ve got palatial gardens. It’s the most effective of the spray and go cleaners.
Key specs - Quantity: 5 litres; Can you use it without a pressure washer: Yes
Price: £8 | Buy now from Amazon
If you’re worried about pets, nearby plants and roaming wildlife, you might be understandably reluctant to spay your patio or decking with a bunch of unknown chemicals or some bleach-heavy fluid. Algon Organic is based on a non-toxic, pet-safe acetic acid that shouldn’t do any serious harm to anything, although it will scorch the leaves of plants on contact. You can even use it around your pond, although it’s advisable to try and avoid any runoff.
It’s certainly easy to use; just clear your patio or decking of any surface dirt, then spray it on with a garden sprayer. After that you can just leave it for a few days while it attacks your mould and algae, and it’ll then keep the surface clean for another year. While it’s not as effective as the heavy-duty cleaners when it comes to tackling long-term staining, we still had great results on paving, decking and garden furniture, bringing green-grey areas back to their original stone or wood. Forgive the slightly unpleasant vinegar smell that sticks around for a day or so after drying, and this one’s a rock-solid cleaner that won’t upset the local critters.
Key specs – Quantity: 2.5 litres; Can you use it without a pressure washer: Yes
Price: £17 | Buy now from Screwfix
As the name suggestions, this is a patio cleaner that is all about planning for the future. The idea is that any future spillages (such as oil, dirt or moss) should be easier to clean the next time around.
It’s simple to apply – you just spray it onto the stone paving (a garden pump sprayer is fine) but don’t let it pool in the contours as it can stain. We had a garden brush handy to spread any excess. It doesn’t give a glossy look, like some sealers, so only use it if you prefer the more natural look. And be warned you might need a couple of coats. Even so, it offers great value for good protection.
Key specs – Quantity: 5 litres; Can you use it without a pressure washer: Yes
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Price: £10.50 | Buy now from Candor Services
Nilfisk is unique as a pressure washer manufacturer in offering such a wide range of detergents and while they’re designed to be used with Nilfisk pressure washers (which are up there with Kärchers in terms of quality), you can (subject to warranty conditions) use them with some other brands.
The company does a very good Stone and Wood Cleaner as its entry-level, basic detergent for cleaning patios, but it’s the Stone Plague Cleaner that really won us over, cleaning any plague off stones, tiles and concrete – including black spot that stays stubbornly there even after a jetwash.
For the ultimate finish, complete the job with Nilfisk’s Stone Sealer to prevent further re-occurrence. We tried the products with a Nilfisk 140 Dynamic 140 Pressure Washer/Patio Cleaner, a seriously good precision-control patio cleaner with a long hose and all the accessories you need – plus, it’s quiet.
Key specs – Quantity: 2.5 litres; Can you use it without a pressure washer: No
Buy now from Candor Services
Why not check out our full list of the best pressure washers?
Price: £210 | Buy now from Argos
Taking over from the K4 Full Control in Kärcher’s line-up, the K4 Power Control is a superb pressure washer, with everything you need to get the grime scoured off your patio, or anywhere else around the home. Its secret weapon is its Power Control Gun and matching Power Control Vario lance. You can switch between three different pressure settings and adjust the spray pattern with a twist of the nozzle, meaning you can switch from a high-powered jet to a softer, flatter spray. When you’re blasting off the mould and algae, you get what you need without having to lug around a bunch of different tools.
Of course, there are extra tools if you want them, and we also tested the K4 with the Power Control car and home kit, which comes with the standard Power Control Vario and Dirt Blaster lances, plus a rotating car brush and a foam jet nozzle. What’s more, it throws in the T5 Surface cleaner for sweeping all the grime from your decking, patio or driveway. It’s worth the £90 extra if you need some extra cleaning power.
Buy now from Argos
Price: £129 | Buy now from Amazon
Whether you’ve got a patio, decking or tarmac – or a mixture of all three – this machine with 5.5m hose is a great all-rounder that we found also got cars and garden furniture looking as good as new. All this, and it’s not too big or heavy, with a cord and accessories that fit neatly in the machine, making it a good option for those short on storage space.
With 100 bar max pressure and 370 litres per hour flow rate, it’s not on par with the Nilfisk or Karcher K5, but what it lacks in power it makes up for in simplicity and ease of use and it gets brownie points from us for the adjustable spray nozzle, handy brush and rotating nozzle. For a no-frills, but solid and well-designed pressure washer that will get your patio looking beautifully clean, it’s great. But the instructions could be clearer.
Price: From £299 | Buy now from Amazon
If you’ve got more grime on your mid or large size patio than you think the Makita reviewed above can handle, the Kärcher K4 lets you step up your game. It’s robust, well-made, easy to set up and fast, Most importantly, it has enough force to shift almost anything. The plug-in detergent bottles make using patio cleaning liquid an absolute doddle, and it’s very easy to control, with a great range of different jet strengths.
That means you never need damage more sensitive areas, for example, where the pointing isn’t as good as it was. On the downside, that heavyweight power comes with, well, a heavyweight washer; one that gets pretty tiring to use over longer periods.
Price: £80 | Buy now from Screwfix
If you’ve only got a small patio or decking, why grab a sledgehammer to crack the walnut? Kärcher’s smallest, cheapest pressure washer is less than 40cm high and 22cm wide and weighs just over 4kg unfilled with accessories attached. True, it hasn’t got the power to blast heavy-duty stains from concrete, but it will happily scourge your patio or decking of algae, mould and grime, and it’s great for cleaning up garden furniture, muddy bikes or even cars. What’s more, it’s still compatible with Kärcher’s range of pressure washer accessories.
There’s no detergent foam sprayer included, but it does have a little tube that sits inside a bottle of detergent and sucks the stuff up, which is great as long as you can avoid knocking over the bottle while you’re cleaning. It’s also worth mentioning that, for its size, it makes an awful lot of noise. Have modest needs and a matching budget? This is the pressure washer to buy.
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