How to Remove Black Spots from a Patio (The Complete Guide)
Black spots on a patio are one of the most common — and frustrating — problems for UK homeowners. They appear on almost every type of patio surface, from natural stone to block paving, and they're notoriously difficult to shift with a pressure washer alone.
Here's everything you need to know about removing black spots from your patio for good.
What Are Patio Black Spots?
Patio black spots are caused by a type of algae called Gloeocapsa magma — a cyanobacteria that thrives in damp, shaded conditions. Unlike green algae, which sits on the surface, black spot algae embeds itself into the pores of the stone, which is why pressure washing alone rarely removes it completely.
Which Surfaces Get Black Spots?
Black spots can affect almost any outdoor surface, including:
- Indian sandstone, limestone, York stone & travertine (natural stone)
- Marshalls, Bradstone & other manufactured paving slabs (artificial stone)
- Block paving & brick driveways
- Porcelain patio tiles
- Concrete & resin surfaces
How to Remove Black Spots — Step by Step
The right product depends on your surface type. Choose from the options below:
Natural Stone (Indian Sandstone, Limestone, York Stone)
Use Patio Black Spot Remover For Natural Stone. Available in 2 litre (treats up to 10m²) and 4 litre (treats up to 20m²).
- Pour into a garden sprayer and apply generously to the surface.
- Leave for 2 hours to allow deep penetration.
- Rinse off with a pressure washer.
- Repeat if needed for heavily stained areas.
Artificial Stone & Paving Slabs (Marshalls, Bradstone, Concrete)
Use Patio Black Spot Remover For Artificial Stone. Also works on porcelain, resin driveways and composite decking.
Block Paving & Brick Driveways
Use Patio Black Spot Remover For Block Paving. Specially formulated to penetrate block paving without damaging the sand or structure beneath.
How to Stop Black Spots Coming Back
Once your patio is clean, apply Patio Black Spot Preventer For All Stone Types annually. It works on every surface type, removes algae within 3–5 days, and prevents black spot from returning — without the need for pressure washing.
Apply it 12 months after your initial removal treatment for best results.
Is It Safe for Pets, Plants & the Environment?
All of our patio black spot products are acid-free, biodegradable, and pet-safe. They can be rinsed onto lawns and flower beds without harming plants or soil.
Ready to tackle your black spots? Shop our full range of Patio Black Spot Removers and find the right product for your surface.