Algae, lichens, liverworts and moss on hard surfaces

It is common to find growths such as algae, lichens, liverworts and moss growing on hard surfaces. Contrary to popular belief, they do not damage what they are growing on, but can cause patios, drives, paths and steps to become slippery.

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Algae on paths can make them slippery. Image: John Trentholm/RHS

Quick facts

Common name Algae, lichen, liverwort, moss
Areas affected Paths, patios, drives, paving, stone features, garden furniture and fencing
Main causes Damp, humid, shady conditions, clean air and/or poor drainage
Timing More noticeable in winter or after a wet spell, but present year-round

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