Black spots on patios are one of the most common problems homeowners face in the UK. These stubborn marks often appear on stone patios, block paving, and concrete surfaces and can make a patio look dirty even after pressure washing.
In this guide we explain what causes black spots on patios and how to remove them properly.
What Are Black Spots On Patios?
Black spots are usually caused by lichen, a type of organism that grows on stone surfaces.
Lichen thrives in damp conditions and can strongly attach itself to patio slabs, especially:
-
sandstone patios
-
limestone patios
-
concrete paving
-
block paving
Unlike moss or algae, lichen roots itself into the stone, which makes it extremely difficult to remove with water alone.
This is why pressure washing often fails to remove black spots completely.
Why Pressure Washing Doesn’t Remove Black Spots
Many people try to remove black spots using a pressure washer, but this rarely works.
Pressure washing can remove:
-
dirt
-
algae
-
moss
But black lichen remains because it is embedded into the surface of the stone.
Often pressure washing simply removes the top layer, leaving the dark stain behind.
The Best Way To Remove Black Spots From Patios
The most effective way to remove black spots is by using a specialist patio cleaner designed to kill lichen and organic growth.
A quality patio cleaner works by:
-
penetrating the lichen
-
killing the spores
-
loosening the stain
-
allowing it to be rinsed away
This method is far more effective than pressure washing alone.
Step-By-Step: How To Remove Black Spots From A Patio
1️⃣ Sweep The Patio
Remove loose dirt and debris from the surface before applying any cleaner.
2️⃣ Apply A Patio Cleaner
Apply a specialist cleaner designed for removing:
-
black spots
-
algae
-
lichen
-
moss
Allow the product to soak into the surface.
3️⃣ Lightly Agitate The Surface
Use a stiff brush to work the cleaner into the patio surface.
This helps break down stubborn lichen growth.
4️⃣ Leave The Cleaner To Work
Allow the solution time to kill the organic growth.
Many cleaners continue working for several hours after application.
5️⃣ Rinse The Patio
Finally rinse the patio with water or a pressure washer to remove the remaining residue.
Once the lichen is dead, the stains can usually be washed away much more easily.
Best Patio Cleaner For Black Spots
When choosing a patio cleaner it’s important to choose one that is specifically designed to remove organic staining such as:
-
lichen
-
algae
-
moss
-
black spots
Products designed for general cleaning may not remove black spots effectively.
A dedicated patio cleaner will penetrate the growth and break down the staining properly.
For example, Shark Instant Clean is designed to remove black spots, algae and organic staining from patios, driveways and paving.
Can Black Spots Come Back?
Yes, black spots can return over time, especially in damp areas.
To help prevent this:
-
keep patios clean
-
remove organic debris regularly
-
apply a treatment when growth first appears
Regular cleaning helps prevent lichen becoming deeply embedded again.
Final Thoughts
Black spots on patios are extremely common across the UK, especially on natural stone and concrete paving.
While pressure washing alone rarely removes them, using a specialist patio cleaner can effectively break down lichen and restore the appearance of your patio.
Regular maintenance and early treatment will help keep patios clean and prevent stubborn staining returning.