, patios go green fast because we get long damp periods — algae, moss and lichen love it. The best time to pressure wash is when you can get a clean result that dries properly, without damaging joints or turning your patio into a slip hazard again a week later.
A simple rule that works:
Spring and autumn are usually ideal for a proper patio clean.
But there’s a bit more to it if you want the clean to last.
The best time of year
1) Spring: most popular and usually best
Why spring works:
You’re removing winter grime and green build-up
Patio is used more in spring/summer
Milder conditions help it dry
Watch-outs: late frosts can still happen early spring — don’t jet wash if you expect freezing nights.
2) Autumn: the smart clean
Autumn is underrated:
You clear algae before winter damp sets in
You reduce slip risk heading into wet months
It often dries well in early autumn windows
3) Summer: only if you do it right
Summer can work, but:
very hot days can dry detergent too fast and leave patchy marks
you may bake dirt into pores if you’re not careful
you might disturb jointing that then dries too fast before it’s reset properly
4) Winter: generally avoid
Winter is usually the worst time because:
it stays damp longer
it can freeze overnight
patios re-green quickly in low-light wet conditions
The best weather conditions
Aim for:
- A dry spell of 24–48 hours
No heavy rain forecast
Mild temperatures
Patios that don’t dry properly can become slippery again quickly and may track dirt back in.
How often should you pressure wash?
Most domestic patios benefit from:
- 1–2 cleans per year depending on shade, trees, and dampness
More frequent light maintenance if it’s a shaded north-facing area
If your patio is under trees or near constant shade, the longer-term fix is often a combination of:
improved drainage / clearing downpipes
regular sweeping
appropriate treatments after cleaning
How to avoid damaging your patio
Common pressure washing damage
Blown-out pointing/jointing
Etching softer stone
Lifting loose slabs
Water forced under slabs
A safer approach
- Start on a lower pressure and increase only if needed
Keep the nozzle moving — don’t drill one spot
Keep a sensible distance
Avoid blasting directly into joints
- After cleaning block paving, you often need to re-sand joints once dry (depending on surface)
Safety: don’t treat it like just water
Pressure washers can cause injury and create electrical risks. HSE has specific guidance on electrical risks from steam/water pressure cleaners.
Minimum sensible PPE:
Eye protection
Gloves + suitable footwear
Signs it’s time to clean your patio now
Green film that feels slippery
Dark patches and black spotting
Patio looks dull even after sweeping
You’ve got guests coming and want it presentable
Slabs stay wet for ages after rain
When to call a professional
Consider getting help if:
- You have jointing that’s already failing
It’s natural stone and you’re not sure about pressure limits
There’s heavy lichen/algae and you want a longer-lasting result
You want a clean + tidy finish
FAQs: patio pressure washing
Is spring or autumn better?
Both are strong options. BBC Gardeners’ World specifically notes spring and autumn as ideal times for patio cleaning.
Will pressure washing remove weeds?
It removes surface growth, but weeds often return unless joints are re-sanded and maintained.
Can I damage my patio?
Yes — especially joints and softer stone. Start low pressure and avoid blasting joints.