Why Your Patio Goes Green So Fast in Cornwall

You've just had your patio cleaned — jet washed, looking brilliant, like the day it was laid. Then six months later it's green again. Not a little bit green. Properly green. You might think something's wrong with your patio, or that you haven't been keeping on top of it. The truth is simpler: you live in Cornwall.

Our Atlantic climate is almost perfectly designed to grow algae, moss, and lichen on outdoor surfaces. Understanding why it happens — and what to do about it — makes keeping your patio clean much more manageable. It also means you understand why it's genuinely important to deal with, not just for looks but for safety.

What's Actually Growing on Your Patio

The green stuff on your patio isn't just dirt or grime, though it often gets mistaken for it. It's a living biological growth — most commonly a combination of green algae, moss, and lichen.

Green algae is the thin, slippery green film that appears first. It's single-celled and grows incredibly fast in damp conditions. It's what makes surfaces feel slimy underfoot and is the primary slip hazard. On a wet day in Cornwall, a patio covered in algae can be as slippery as black ice.

Moss follows once algae has established a foothold. It's thicker and spongier, holds even more moisture against the surface, and starts to work into cracks and mortar joints over time. Leave moss long enough and it will begin to lift paving slabs and degrade pointing.

Lichen is the crusty, grey-green or orange growth that appears on older, undisturbed surfaces. It's actually a symbiosis of algae and fungi. It's much harder to remove than algae or moss — it bonds directly to the surface — and it's a sign that a patio hasn't been cleaned in a while.

Why Cornwall Is Perfect for Green Growth

Most of the UK gets green patios eventually, but in Cornwall it happens faster and more aggressively than almost anywhere else in the country. There are three reasons why.

We get a lot of rain. Newquay and most of the north Cornish coast see 250 or more rain days per year. The Atlantic doesn't give us much of a dry season. That constant moisture is exactly what algae and moss need to thrive. The patio surface barely dries out between showers for months at a time in autumn and winter.

Our winters are mild. In most of inland Britain, cold winters kill off algae spores and reset the clock. Hard frosts are genuinely effective at clearing growth. But Cornwall — warmed by the Gulf Stream — rarely sees the temperatures that would do that job. Our mild, damp winters are like a spa for algae. The growth doesn't stop; it just slows slightly and then accelerates again come spring.

Salt air adds nutrients. Living near the coast means our air carries fine particles of sea salt. Salt is actually a mild fertiliser for certain biological growths. It deposits on surfaces and gives algae and lichen an extra boost. If your garden is within half a mile of the coast — which describes a lot of Newquay, Perranporth, and Padstow — this is a real factor.

Why It's a Safety Issue, Not Just an Aesthetic One

A green patio looks untidy, yes. But the more pressing concern is the slip risk it creates — and this is something I feel strongly about, especially for older customers.

Falls outdoors are one of the most serious causes of injury for people over 60. According to the NHS and Age UK, falls are the most common cause of injury-related deaths in older people, and outdoor slips on wet or slippery surfaces are a significant contributor. A thin film of wet algae on a patio or path is genuinely hazardous — not just slightly slippery, but capable of causing a full loss of footing on any hard surface.

If you have elderly relatives visiting, or you're finding your own balance and confidence on your feet isn't what it was, a slippery patio is not something to put off dealing with. It's a trip that could lead to a broken hip, a hospital stay, and a long recovery. The good news is it's entirely preventable.

DIY Options: What Works and What Doesn't

There are a few things you can try yourself before calling in professional help. They work — up to a point.

• Patio cleaning chemicals: Products like Patio Magic or Wet & Forget are applied diluted to the surface and left to work over days or weeks. They kill the growth and the surface gradually clears. They're good for light to moderate algae and are gentle enough for most surfaces. The downside is they're slow, they need dry weather to apply, and they don't remove the dead growth — it just fades.
• Bleach solution: Diluted bleach (1 part bleach to 10 parts water) applied with a stiff brush will kill algae and lighten the surface. It's effective but not ideal — it can discolour certain stones, harm nearby plants if it runs off, and it doesn't do anything about deeply embedded moss or lichen.
• Stiff brushing: Good for removing loose moss and debris before treatment, but on its own it doesn't kill the growth or remove algae. Without killing the root cause, the green comes back within weeks.

None of these options get close to the result of a proper pressure wash with the right equipment and the right technique. And on a badly affected surface, they may not be enough to make a meaningful difference to the slip hazard.

What Professional Pressure Washing Actually Involves

A professional clean is a different proposition to a consumer pressure washer from a hire shop or a DIY attempt. Here's what the process looks like when I do it.

First, I clear the area — furniture, pots, anything loose. Then I assess the surface. Different materials need different pressures: natural stone, block paving, concrete, and porcelain all have different tolerances. Too high a pressure on natural sandstone, for example, and you can pit the surface or blast out the pointing.

The wash itself uses professional-grade equipment at the correct pressure for the surface, often combined with a surface cleaner attachment that works in a rotating pattern rather than a direct jet — this gives a much more even finish without streaking. Stubborn lichen patches get pre-treated. Edges, steps, and grout lines all get specific attention.

After the main wash, I clear the waste water and debris and check the finish. I'll also give you honest advice about any pointing that needs attention or any areas where the surface is starting to show wear. A clean patio is a good opportunity to spot issues before they become expensive ones.

How Often Should You Have Your Patio Cleaned in Cornwall?

Inland in the UK, most patios can get away with a clean every two years. In Cornwall, once a year is the right interval for most surfaces. Ideally in spring (to clear winter growth before the summer season) or in autumn (to remove summer growth before the wet months set in and the algae accelerates).

If your patio is in a shaded, north-facing spot — or surrounded by trees or high fences that keep it damp — you may need it more frequently. Shaded surfaces dry out more slowly and provide even better conditions for growth.

If you have a path or steps that people use regularly, don't leave it as long as the main patio area. High-traffic surfaces where a slip could cause a fall should be prioritised.

My Pressure Washing Service in Cornwall

I offer professional pressure washing across Newquay and the surrounding areas of Cornwall, including Perranporth, Padstow, Wadebridge, Truro, and St Austell. I clean patios, driveways, paths, steps, and decking — any outdoor hard surface that's gone green or built up with grime.

I use professional equipment and take the time to do the job properly. That means the right pressure for the right surface, clean edges, and a finish that actually lasts. Not a rushed blast that leaves half the algae behind and strips the pointing out of the joints.

If your patio is looking a bit sorry for itself — or if it's become a genuine slip concern — give me a call. I'm happy to take a look and give you a straight quote with no obligation.