Black spot lichen on paving: how to remove it

Outdoor paving can gradually develop grey-green or black patches of lichen, algae and moss. The growth makes patios and driveways look dull and can become slippery, especially when wet. This guide explains why it appears and how to remove it.

What grows on outdoor paving?

Algae, moss and lichen can grow on outdoor paving, taking hold in small surface pores and joints. Simply removing the top layer may allow the growth to return, so it helps to understand the problem before choosing a cleaning method.

Why does growth appear on paving?

Growth thrives in damp, shaded areas where the paving sees little use. It is often worst on north- and east-facing surfaces, beneath trees and shrubs, and on patios and driveways that are rarely used. More moisture and less sunlight allow it to develop faster, which is why it often returns in the same places each year.

How to remove growth from paving

There are several ways to do this. Which one is best depends on how bad the problem is and what kind of paving you have.

Brown soft soap and a stiff brush

Brown soft soap mixed with lukewarm water and a stiff brush is the gentlest option. It works best on light green growth. Scrub the paving thoroughly, leave the soap to work for a few minutes, then rinse with a garden hose. It is gentle on the joints, but it takes effort and will need repeating.

Boiling water

Boiling water poured directly onto algae and moss kills some of the growth immediately without cleaning chemicals. It can be useful for small patches between paving slabs or on a step. The discolouration still needs removing, and the effect lasts only until new growth appears. Take care to avoid splashing your legs or plants you want to keep.

Algae remover for paving

A liquid outdoor algae remover penetrates and breaks down algae over time. Follow the dosage and treatment time on the container. Many products continue working for a while after application. Take care around drains, plants and pets while you work.

Pressure washer

A pressure washer removes visible growth quickly, giving an immediate result. Too much pressure, however, can dislodge jointing sand and damage softer paving, leaving a rougher surface where growth takes hold more easily. Use moderate pressure, keep the nozzle at a consistent distance and top up the jointing sand afterwards.

Professional cleaning and algae treatment

Professional treatment cleans beyond the visible surface. The method is matched to your paving, followed by treatment to slow the return of algae without damaging the joints. It is particularly worthwhile for large areas, recurring growth or paving that cannot withstand harsh cleaning. To find out what it would cost for your patio, you can get a no-obligation quote for paving cleaning and algae treatment. You'll receive a fixed price before we start.

What lasts longest?

Brown soft soap, boiling water and algae remover can help maintain a small patio. Because growth can take hold deep in the surface pores, these methods usually need repeating. Professional algae treatment combines thorough cleaning with a treatment to slow new growth. This can mean less maintenance for you and less risk of damaging the joints.

How to keep paving clear

Once the patio is clean, you can do a lot yourself to keep it that way:

• Make sure water can drain away so the paving does not stay wet.
• Trim bushes and branches back to allow more sun and air.
• Sweep away leaves and seeds regularly to keep the surface clean.
• Have the paving sealed after cleaning to reduce open pores and make it harder for algae to take hold.

Spring and early summer are the best times for this work. The paving dries quickly, and treatment gets ahead of the season's growth.

When should you get help?

You can tackle a small patio yourself from time to time. Professional help makes sense for large areas, recurring growth, or old and delicate paving that is easily damaged. If you want a lasting result without starting again next season, we are happy to discuss the job with no obligation.

Frequently asked questions

What is the growth on outdoor paving?

Outdoor paving can develop algae, moss and lichen. These living growths take hold in surface pores and joints.

How do you remove growth from paving?

Options include brown soft soap and a stiff brush, boiling water, an algae remover or a pressure washer. Professional algae treatment combines a cleaning method suited to the paving with treatment to slow new growth without damaging the surface.

Does brown soft soap help remove growth from paving?

Yes, brown soft soap and a stiff brush can remove light green growth while being gentle on the joints. It takes effort and will need repeating.

Can you use boiling water on algae?

Boiling water kills some algae and can help with small patches. It does not remove the discolouration on its own, and the effect is temporary.

Why does growth return to paving?

Damp, shaded conditions allow new growth to develop. If you only remove the visible layer, it can return quickly. Applying an algae treatment after cleaning can keep it away for longer.