Ask the head gardener: What's the best way to clean my patio?

Telegraph

28-02-2025

Dear Tom,
After the recent wind and rain, my patio is looking awful, and is covered in leaf debris and algae. I don't own a pressure washer – what's the best way to clean it?
–Jane
Dear Jane,
After the winter, a layer of dirt, grime and algae can build up on patios and pathways. Not only does it look awful, but I'm sure that I'm not the only one who has recreated a marvellous Torvill and Dean impression and nearly fallen over as the surface becomes increasingly slippery and unsafe. Cleaning the patio is one of those tasks that we should address, and there are many ways to approach it. The methods to clean a patio can range from the industrial pressure washer right the way through to a bucket of soapy water and a good scrub.
There are a number of patio-cleaning products that are available to buy both online and from garden centres, but there are many solutions that we can make at home that work well and won't cost very much. Before starting any cleaning operation, remove any leaves or plant material from your patio with a leaf blower or brush, and all of that debris can be added to a compost heap. Once you've cleared all the moss and debris, as well as any furniture that may be positioned on the patio, then the cheapest and easiest method would be to fill a bucket with warm water and add a good squirt of washing up liquid. A stiff broom and a good dose of elbow grease will start to lift any of the grime from the slab, making sure that you work the brush in different directions across the whole surface. Rinse off the area with the hose and leave it to dry. It may require a second scrubbing if the paving was particularly grubby.
The other homemade remedy is to use household vinegar, ideally white vinegar as opposed to malt vinegar. When using vinegar, be aware that it is corrosive and has the potential to damage plants, as it's often used as a weed killer, so dilute any runoff from cleaning the patio with clean water to reduce any damage. Make up a bucket of a 50:50 mix of water and vinegar and apply it to your patio using a sprayer or a brush. Leave to soak in for 30 minutes and then scrub thoroughly with a hard bristled brush. Allow to dry and repeat if necessary.
For particularly stubborn grime on patios, an electrically powered pressure washer will give a far more thorough result compared with hand scrubbing. The cost and the noise involved with either buying or hiring this piece of equipment is worth considering, as well as the amount of water that is required to clean the patio being far greater than that of hand scrubbing. You will need an electrical supply or a generator, as well as a water supply with reasonable pressure to sustain a pressure washer, and there is obviously the added hazard of mixing electricity and water, so care is needed. Make sure you're wearing a good pair of wellington boots, waterproof trousers and jacket, and goggles, as it's a messy business. Start at one end of the patio and hover the nozzle around 30cm (12in) away from the paving, lifting any grime and dirt with a sweeping action, pushing the dirty water in one direction away from the area that you've cleaned. You may have to go over some areas a couple of times or overlap the previous stroke to ensure that all grime and algae has been removed. At the end of the job, raise the nozzle higher for a gentler action to rinse off any areas. Check any walls, doors and windows which may need cleaning off as well.