How to Clean a Patio: Remove Black Spots, Algae, and Green Growth

Over time, patios can lose their fresh look as black spots, algae, and green staining appear. These marks are common, but with the right approach, they can be removed to restore your patio’s original finish.

Key Takeaways

• Black spots are caused by fungal spores that settle in porous paving.

• Algae and green growth thrive in damp, shaded areas.

• Cleaning methods include scrubbing, pressure washing, and specialist treatments.

• Prevention is as important as cleaning — regular maintenance keeps stains away.

• Different paving types need different cleaning approaches.

Understanding Black Spots on Patios

Black spots are stubborn fungal growths that can penetrate the surface of natural stone, concrete, or other porous materials. They are especially visible on light-coloured paving such as sandstone.

Common causes:

• Fallen leaves and organic matter.

• Moist conditions.

• Lack of regular cleaning.

Algae and Green Growth

Algae and moss appear when damp conditions and shade combine. You’ll often see them in the corners of patios or on north-facing areas. Aside from looking unsightly, they can make the surface slippery and unsafe.

Cleaning Methods for Patios

1. Pressure Washing

A pressure washer can remove dirt, algae, and loose debris. Use with care on softer materials such as sandstone to avoid surface damage.

2. Specialist Cleaners

Products like Patio Black Spot Remover or sodium hypochlorite-based cleaners are effective for black spots. Follow the manufacturer’s safety instructions.

3. Vinegar and Natural Methods

A vinegar solution can help lift green algae on some surfaces. Avoid using it on acid-sensitive stone like limestone.

Removing Black Spots from Natural Stone Paving

Natural stone, such as that used in garden patios, needs a careful approach.

• Apply a specialist cleaner and allow it to soak in.

• Scrub with a stiff brush.

• Rinse thoroughly with clean water.

How to Stop Patios Going Green

Preventative steps:

• Brush the patio regularly to remove debris.

• Cut back overhanging plants to let in more sunlight.

• Use a patio sealant to make the surface less absorbent.

A professional paving company can also apply commercial-grade sealants that last longer than DIY versions.

Dealing with Algae on Porcelain Patios

Porcelain paving is less porous and easier to clean. Usually, a mild detergent and water are enough to remove algae or dirt. For stubborn marks, a non-acidic outdoor cleaner works best.

Final Word

Cleaning a patio doesn’t just improve its appearance - it makes it safer to use. With regular maintenance, you can keep your patio looking new for years.