Moss colonises driveway surfaces that remain damp and shaded for long periods, and once established it creates a slip hazard as well as looking unsightly. Addressing it requires killing the moss at the root rather than simply sweeping it away, combined with measures to reduce the conditions that encourage its return.

Killing the Moss

Apply a diluted solution of a proprietary moss killer, patio cleaner, or household bleach to the affected areas. Dilute bleach to around one part bleach to five parts water and apply with a watering can or garden sprayer, ensuring the solution saturates the moss. Leave it to dwell for at least 30 minutes, or preferably longer, to kill the moss at the base before disturbing it. The moss will turn brown to black as it dies. Proprietary moss killers may require a longer dwell time; follow the product instructions.

Removing the Dead Moss

Once the moss is dead, scrub the surface with a stiff brush to dislodge the material, then pressure wash to remove the debris. Working from one end of the driveway to the other in overlapping strips removes the dead moss and any residual treatment product. A surface cleaner attachment on the pressure washer produces more even results than a hand lance and reduces streaking on block paving and concrete surfaces.

For block paving, re-sand the joints with kiln-dried jointing sand after washing, as pressure washing displaces the sand between the blocks. Resanding restores stability and makes the surface less hospitable to future moss growth by filling the spaces where moss spores settle.

Preventing Regrowth

Moss returns fastest on surfaces that remain damp. If the driveway is in a persistently shaded area under overhanging trees or adjacent to a north-facing wall, reducing the shade by trimming vegetation improves drying and slows regrowth. A penetrating sealer applied after cleaning reduces the porosity of concrete, tarmac, or block paving surfaces, making them less hospitable to moss establishment.

A preventive biocidal treatment applied annually after cleaning inhibits moss and algae regrowth. These treatments are available as liquid concentrates for dilution and application with a garden sprayer and are far less effort than repeated removal of established growth.

Summary

Remove driveway moss by applying a moss killer or diluted bleach, allowing it to dwell, then pressure washing. Re-sand block paving joints after washing. Apply a surface sealer and annual preventive biocide to inhibit regrowth. Improving light and drainage by managing overhanging vegetation addresses the underlying cause of persistent moss growth.