Killing lichen on concrete. Here is a guide.

Killing lichen growth on the Gladstone Entertainment Centre
Professional lichen cleaning services

Step 1: Prepare Lichen-Killing Mix

Use a sodium hypochlorite-based soft wash mix for best results.

Recommended Mix:

  • 1 part 12.5% pool chlorine (sodium hypochlorite)

  • 3 parts water

  • Add dishwashing detergent or a softwash surfactant (e.g. “Green Wash”, “Agent Clean”): ~50–100 ml per 5L of mix

This creates an approx. 3% sodium hypochlorite solution that clings well to concrete.

Step 2: Application

  • Apply generously using a pump-up sprayer, backpack sprayer, or softwash system

  • Focus on areas with visible lichen growth

  • Let it dwell for 20–40 minutes, but do not let it dry out – reapply mist if needed

  • You’ll see the lichen bleaching white or yellow – that means it’s dying

Step 3: Rinse and Remove

After dwell time:

  • Pressure wash the concrete at 2500–5000 PSI with a surface cleaner (preferred) or turbo nozzle

  • Most of the lichen should lift off easily. Any black roots still attached will die and fade over the next few weeks

  • Lichen invades the surface and remnants may remain although they are dead

  • Rinse well to remove chemical residue

Step 4: Prevention

  • Apply a biocide (like Benzalkonium Chloride) every 6–12 months

  • Keep areas well-drained and clean of leaf litter or organic debris

⚠️ Safety Tips:

  • Pre-wet any nearby plants or grass, and rinse after

  • Always wear gloves, eye protection, and a mask

  • Avoid run-off into drains or stormwater systems