Patios, stone paving areas, and driveways are perfect breeding grounds for a recurring problem we face annually. These areas and surfaces gather a build-up of an unpleasant green substance which is not only an eyesore, but it also becomes slippery and dangerous.

In most cases, your patio area is turning green from the growth of algae, lichens, liverworts, and moss. These tend to grow in the shade when the weather is damp and cool.

Fortunately, this a naturally occurring issue that has a relatively easy fix.


Algae are most likely the source of the green colour that appears on your patio. It is a wet, almost jelly-like substance.


Lichens appear on surfaces like timber as well as paving and stone. They are dryer than algae and look leaf-like or crusty.


Liverworts are green in colour and appear like flattened plants with no leaves.


The most commonly known of the four, moss is soft, dense, and green in colour. It often covers hard surfaces like walls, patios, and driveways.

Are algae, lichens, liverworts, or moss dangerous?

For the most part, algae, lichens, liverworts, and moss that appear on your outdoor surfaces do not pose health hazards. However, they should never be ingested, and you should wash your hands if you come in direct contact with some.

The main danger they pose is their ability to make a surface slippery.

How Can I remove Algae from my patio?

Algae, lichens, liverworts, and moss are relatively easy to remove. They do not permanently stain or damage the surfaces that they live on. Here are some practical solutions for removing them:

Use a yard brush

Use a yard brush with wire bristles to remove the green build-up. If the bristles don’t reach through cracks or gaps, try using a knife or flat object to clear out those hard to reach areas.

Pressure wash the area

Use a pressure washer or other outdoor cleaning methods (wet blasting, grit blasting, JOS and TORC cleaning) to remove the algae, lichens, liverworts, and moss. This should effectively remove the green staining also.

Ensure that you properly drain the area, as failure to do so will result in another build-up of algae and moss.

Hire professionals

Professional cleaning services such as Token cleaning deal with this type of issue daily. They have the equipment, tools, and expertise to clean your stained surfaces with ease.


Token Cleaning - before and After Patio Clean

Before and after cleaning treatment


How do I prevent further build-up of Algae

Effective drainage

Try to avoid water and moisture from stagnating on surfaces. Water can be a catalyst for the growth of most algae and moss.

Brush regularly

Regularly brushing your patio with a wired or firm brush can prevent another build up of algae.

Use the right weedkiller

Consult your local hardware store or garden centre for expert advice on what weedkiller you should use. As a rule of thumb, most patio and surface cleaners will help with the removal of algae, lichens, liverworts, and moss, but repeat use is necessary to keep them at bay.