Why your patio turns green every winter (and how to actually stop it)
You cleaned it in spring. By November, it's green again, slippery underfoot and dotted with black spots that won't budge.
It's not bad luck. Autumn and winter are the perfect conditions for algae, moss and lichen to take hold on patios, paths and driveways. Here's why it happens, what you can realistically do about it yourself, and how to stop it coming back every year.
Why your patio goes green in autumn and winter
Shorter days, constant damp and low sunlight give green growth everything it needs. Shaded corners and north-facing patios that never fully dry out are hit hardest.
Three culprits are usually behind it:
- Algae. The green, slimy film that makes paving dangerously slippery after rain.
- Moss. Creeps in along joints and edges, holding moisture against the slabs.
- Those stubborn black or grey spots. It bonds tightly to the surface and is the one most people struggle to shift.
Fallen leaves make it worse. Left to sit, they trap moisture, stain paving and feed the next round of growth.
And it's not just about looks. A green, slippery patio is a real slip risk on dark, wet winter mornings, and dirty, porous paving is more prone to frost damage.
What you can do yourself
A bit of regular upkeep helps keep things under control between professional cleans:
- Sweep regularly. Get fallen leaves and debris off before they sit and stain, especially through October and November.
- Pull weeds from the joints. Weeds hold moisture and loosen jointing over time.
- Give it a gentle scrub. Warm water, a mild cleaner and a stiff brush will lift surface dirt. Always patch test first, as some products can mark natural stone.
- Keep drains and gullies clear. Standing water is what green growth loves most.
These steps keep your patio tidier for longer. What they won't do is deal with growth that's already taken hold.
Get 10% off hard surface treatments
Rather leave it to the experts? Get 10% off hard surface treatments until 30 November.
Where DIY falls down
Most DIY cleaning treats what you can see, not what's causing it. That's why so many patios are green again within months.
- Pressure washers can do more harm than good. Blasting at close range can strip out jointing, roughen the surface and open up the pores in the stone. That gives algae and moss even more to grip onto, so it comes back faster.
- Lichen won't shift with a scrub. Those black spots are bonded to the surface. Household cleaners and elbow grease rarely touch them.
- The wrong product can cause damage. Bleach, vinegar and acidic cleaners can stain, etch or discolour natural stone like sandstone and limestone.
- It's hard, slow work. A properly scrubbed patio is a full weekend on your knees, often in the cold and wet.
- It doesn't last. Without treating the growth itself, it's usually back by spring and you're starting again.
What a professional treatment does differently
A professional hard surface treatment tackles the growth itself, not just the surface grime, so your patio stays cleaner for longer.
- Treats the cause. Trained technicians apply a professional-grade, biodegradable solution that breaks down algae, moss and lichen at the root, rather than just blasting the surface.
- No damage. The right method for your surface, whether that's natural stone, concrete slabs or block paving, with no risk of blasting out the joints.
- Longer-lasting results. We recommend four hard surface treatments in the first year, then three a year after that to keep things looking their best. Most customers see cleaner surfaces for many months, far longer than a jet wash.
- Done for you. Your local expert does the work, so there's no weekend lost to scrubbing.
- Covers more than the patio. Paths, driveways, steps and other hard surfaces can be treated at the same time, and hard surface weed control can be added to stop weeds coming back in the joints.
An honest word on lichen. Those black spots are the toughest thing to treat on any patio. Lichen is very difficult to eradicate completely and needs multiple treatments, but you'll see a noticeable improvement after each visit.
Get your patio winter-ready
Don't let another winter of green, slippery paving catch you out. Our local experts will treat your patio, paths and driveway so they stay cleaner and safer for longer.
Get 10% off our hard surface treatments when you book before 30 November. Open to new and existing customers.
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