How to remove black spots from patio – a step-by-step guide to clean paving

If you're wondering how to remove black spots from a patio, you're not alone: it's common issue that many of us will face from time to time, and it can be an eyesore in any outdoor space.

'Whether your patio is made up of natural stones or patio slabs, they will inevitably show some form of biological growth over the winter and spring months, such as algae and mould,' says Jonathan Kirby, garden expert at Roxil. 'But you can follow a few simple steps to tackle black spots.'

So, before you accept that your patio ideas have been defeated, know that it is possible to remove the signs of mould and mildew settling into your paving stones – and while the best patio cleaners can help, there other natural ingredients you can use if you're deciding how to clean your patio.

Black spots on a patio don't have to be permanent. We've asked the experts how to remove black spots from a patio, so you can get back to enjoying your patio area without distraction.

Dr. Jonathan Kirby

Dr. Jonathan Kirby is a developmental chemist at Roxil, Safeguard Europe. From pest control to masonry protection, he has dedicated himself to helping protect UK housing stock through the development of new and innovative materials. Jonathan is the go-to garden expert at Roxil for tips on how to protect garden patios, paving and outdoor wooden structures from the elements.

How to remove black spots from patio

Our guide will tell you how to remove black spots from the patio in five simple steps. First, you'll need a few supplies before you can crack on with cleaning the patio.

What you'll need

• Sweeping brush: for sweeping away loose debris, like these sweeping brushes from Amazon
• Patio cleaner: there are plenty of Amazon patio cleaners that make faster work of removing black spots, or you can use white vinegar and baking soda for a chemical-free clean
• Rubber gloves: stock up on these Amazon rubber glove deals to protect your hands
• Hard-bristled hand brush: one of these hard-bristled hand brushes from Amazon will help to maximise your scrubbing efforts
• Hose: use these garden hose pipes from Amazon to rinse the area if you have an outdoor tap, or simply wash away with a bucket and water

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Step-by-step

1. Get prepped for cleaning

The first step to learning how to remove black spots from patio is to grab your brush and sweep away any debris. Dirt, gravel, leaves, and anything else that likes to find a home on your patio needs to be removed before moving on to the next step. Make sure to clear the space of any plant pots or garden furniture, too.

2. Choose your cleaner

Black spots show up on patio slabs when mould and algae have taken root in the pores of the flags.

'I recommend using a specially formulated black spot remover, such as Rob Parker's Best Patio Cleaner,' says Ivo Iv, founder of Decor Home Ideas. 'This product can be used on all types of stone surfaces and will not only kill the black spot permanently but also bleach the blackness out of the visible black spot.'

There are plenty of mould-removing patio cleaners on the market – just double-check that they're safe to use on your patio's material. 'Watch out for acid or bleach-based cleaners as these can damage the patio surface, and instead opt for a soft, non-destructive patio cleaner,' Jonathan says.

Wet & Forget Mould, Lichen & Algae Remover - 5 Litre, was £34.99 now £26.38 at Amazon

The Wet and Forget Mould, Lichen and Algae remover has a non-bleach formula that is ideal for cleaning any type of patio surface. Mix one part product to five parts litre for effective removal of black spots, and you'll be able to use it 30 times over if they come back.

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3. Or, make a natural cleaning solution

You can also try cleaning with vinegar or baking soda. These are powerful cleaning agents that help to decompose bacteria, and they work wonders for removing mould and mildew from outdoor cushions. Experts say they can do the trick for the patio as well.

'You can remove black spots easily from patios in an eco-friendly, low-cost way with white vinegar,' says Laura Harnett, Founder of Seep. 'It has antifungal and antibacterial properties and will also stop the mould or lichen from growing back. Mix a paste in a bowl using one part baking soda, one part white vinegar and one part hot water.'

3. Apply your cleaner

Next, apply your chosen cleaning agent to your patio. Be generous – the more solution you apply, the more likely those black spots will lift. Wait at least 15 minutes before moving on to the next step, to allow the solution to work its magic. Special patio cleaners may need longer to activate, with some products recommending you wait 24 hours before scrubbing, so check the manufacturer label after you apply.

'Wear gloves to protect the skin and then apply the cleaner with a spray or wire brush, either neat or diluted depending on the size of your patio,' says gardening expert Jonathan.

4. Scrub it

'Grab a stiff-bristled brush and scrub the black spots,' says Sarah Clemence, cleaning blogger at Busy Blooming Joy. 'Put some elbow grease into it, and you'll see them start to disappear.'

How much scrubbing you need to do will depend on how many black spots are on your patio, and the type of cleaner you're using. White vinegar and baking soda solutions will need to be worked into the slabs in order to activate. Some patio cleaners will do most of the work for you, and you may find after leaving it to sit on your patio for 24 hours that most of the black spots have lifted.

5. Rinse away

'Finally, rinse the area with water, either with a hose or a low-pressure setting on one of the best pressure washers – high pressure might damage the pointing between slabs,' says Sarah.

As your cleaning solution washes away, the black spots on the patio should disappear with it. You may need to repeat the process for stubborn spots which have settled on your patio for a while.

And that's it! Five simple steps and you've successfully learned how to remove black spots from a patio.

FAQs

What causes black spots on patio slabs?

'Black spots on patio slabs are often caused by mould, mildew, or lichen growth because of moisture and shade,' explains Amber Noyes, horticulturist and editor at Gardening Chores. 'It's essential to tackle this issue as soon as you notice it because these organisms can damage the patio over time.'

Not waterproofing the patio or installing adequate drainage is one of the most common patio mistakes you can make, and will lead to black spots appearing on your slabs more frequently.

'Black spots require moisture to grow and then take root in the pores of the patio flags,' explains Jonathan from Roxil. 'This is why it’s so important to waterproof the patio when laying it to prevent the black spots from arising in the first place.'

Does bleach remove black spots on patio?

Bleach can remove black spots from patio, but it's a harsh chemical that will potentially damage some paving materials. It's also not good for the environment, and something you should avoid using if you've got plants near your patio area.

'I prefer using a vinegar solution as it's more environmentally friendly and less harsh on your patio surface,' says Amber Noyes. 'If you decide to use bleach, dilute it with water (1 part bleach to 10 parts water) and wear protective gear, such as gloves and goggles.'

Does washing powder remove black spots on a patio?

'Yes, washing powder can help remove black spots on a patio,' says Samantha Richards, garden gazebo expert at Gazeboshop. 'It contains surfactants and enzymes that can break down organic matter and grime.

'This method is generally less harsh than using bleach and can be effective for lighter stains. Here’s how to use it:

1. Mix washing powder with a little water to form a paste
2. Spread the paste over the black spots
3. Use a stiff brush to scrub the areas
4. Let the paste sit for about 15-30 minutes
5. Rinse the patio thoroughly with clean water.

So, now you know how to remove black spots from a patio – and you can pick whichever ingredient suits you.

So, now you know how to remove black spots from a patio – and you can pick whichever ingredient suits you.