How to clean a patio after a wet Lincolnshire winter

A wet winter is hard on outdoor surfaces. By the time spring arrives, most patios across Lincolnshire are coated in a layer of green algae, black spots and general grime that makes them look years older than they are. The good news is that knowing how to clean a patio after a wet winter — and doing it in the right order — can restore it to something close to new in a single afternoon.

Here's what actually works, from assessment through to aftercare.

Why winter does so much damage to patios

It's not just the rain. It's the combination of low light, persistent damp and weeks of near-freezing temperatures that allow algae, moss and black spot fungus to take hold. North-facing patios in places like Nettleham or Washingborough can spend whole months in shade, and those conditions are ideal for biological growth to spread across every surface — grout lines, slab faces, even raised edges.

ByDecember, your patio might look fine. By March, the damage done since October becomes visible all at once as temperatures rise and the growth turns vivid green.

Step one: assess before you start

Before you reach for a pressure washer or a bottle of patio cleaner, take ten minutes to look carefully at what you're actually dealing with.

• Type of surface. Natural stone (sandstone, limestone, Indian sandstone), concrete slabs, porcelain and block paving all need different approaches and different pressure levels.
• Condition of pointing and jointing. If your grout or kiln-dried sand is already loose, high-pressure washing will make it worse.
• Type of growth. Green algae wipes off more easily than black spot or lichen, which need longer dwell times with the right product.
• Any efflorescence or staining. White salt bloom or rust marks need targeted treatment rather than just a wash.

Getting this right first saves you from making things worse.

Step two: treat biological growth before washing

This is the step most people skip, and it's probably the most important one.

Apply a diluted patio biocide or algaecide across the whole surface and let it dwell for the time specified on the product — usually 20 to 30 minutes, sometimes longer for heavy moss or established lichen. This kills the root structure of the growth rather than just lifting the surface layer. If you pressure wash without doing this first, you'll shift the visible colour but leave the biology behind, and it will return within weeks.

For natural stone surfaces in particular, check that the product is pH-neutral. Acidic cleaners will damage limestone and some sandstones even at low concentrations.

Step three: pressure wash correctly

Once the biocide has had time to work, you're ready to wash. A few key points:

Choose the right nozzle and pressure

For most patio surfaces, a 25-degree fan nozzle at 100–150 bar is plenty. Porcelain can handle more; older natural stone should have less. A rotary or turbo nozzle gives a more thorough clean but must be kept moving on softer materials.

Work methodically

Start at the highest point of your patio and work downhill so dirty water runs away from cleaned areas. Overlap each pass slightly. Get into grout lines with a dedicated grout-cleaning nozzle or a narrower fan — this is where most of the black spot hides.

Don't hold the lance too close

With block paving or pointing that's seen better days, holding the nozzle within a few centimetres will strip jointing sand rapidly. Keep a consistent distance — around 20–30 cm for most surfaces — and let the dwell time from step two do the heavy lifting.

If you're in any doubt about pressure levels or your surface is particularly old or delicate, this is a sensible point to call in a professional. We cover patios across Lincolnshire from Lincoln itself out to villages like Branston, Heighington and Saxilby — you can see the full list of areas we cover and get a sense of what's involved.

Step four: rinse thoroughly and inspect

Rinse the whole surface with a low-pressure wide fan to clear any remaining cleaning product and lifted debris. Then let it dry for a couple of hours — you'll see a much clearer picture of what's been shifted and what hasn't.

If stubborn black spots remain, a second application of biocide and a targeted re-wash usually clears them. Don't scrub hard with a stiff brush on natural stone — you'll scratch the surface.

Step five: re-sand block paving and re-point if needed

After washing block paving, the kiln-dried jointing sand will almost certainly need topping up. Brush dry sand into the joints and compact it gently. If pointing on natural stone or concrete slabs is crumbling or missing, it's worth repointing properly before the next winter — open joints let water in to freeze and expand, which speeds up further deterioration.

Should you seal the surface after cleaning?

Sealing after a thorough clean is one of the most effective ways to slow regrowth and make future cleaning much easier. It's not always necessary — porcelain, for instance, doesn't need sealing — but for Indian sandstone, concrete and block paving it can make a real difference to how your patio looks in twelve months' time. Our patio cleaning topic hub covers the sealing question in more detail if you want to read more before deciding.

When to call a professional instead

DIY cleaning works well when you have the right equipment, some patience and a surface that's in reasonable structural condition. But if your patio has:

• Heavy lichen or deeply ingrained black spot that's resisted previous attempts
• Cracked or loose slabs that need lifting before washing
• Pointing that's largely gone and needs full reinstatement
• A delicate natural stone surface you're not confident about

…then a professional clean is likely to give you a better result and avoid accidental damage. We've restored patios across Lincolnshire that homeowners had almost given up on, from Cherry Willingham to Skellingthorpe. Take a look at our outdoor surface cleaning services to see what we cover.

Get your patio looking its best this spring

If you'd rather have it done properly and not spend your weekend wrestling with a hired pressure washer, we'd be happy to take a look. Request a free quote and we'll get back to you quickly with a straightforward price for your patio, path or driveway.

Frequently asked questions

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Need a hand with yours? We cover Lincolnshire for patios, driveways, paths and more — see the areas we cover or browse our services. Get a free quote or call 07874 010739.