How to remove lichen from concrete

Bad lichen on concrete
Bad lichen on concrete that can be cleaned easily

Lichen, a symbiotic organism composed of algae and fungi, can be a common sight on concrete surfaces, especially in damp or shaded areas. While lichen is not harmful to concrete, its presence can create unsightly stains and potentially lead to surface deterioration over time due to moisture retention. If you're looking to clean up your concrete surfaces, here's a comprehensive guide on how to remove lichen effectively.

Understanding Lichen

Before diving into removal methods, it's essential to understand what you're dealing with. Lichen thrives in moist environments and can be found in various colours, including green, yellow, and grey. It adheres firmly to surfaces, making it somewhat challenging to remove without the proper technique.

Hiring a professional

Before undertaking this project, it may be worth contacting a professional cleaning company who generally us sodium hypochlorite to eradicate lichen and treat surfaces for longer cleanliness. One recommended company is Cleanupcrew. A link to see their successes



Safety is paramount when dealing with chemicals or manual cleaning of surfaces. Wear protective gear, including gloves, eye protection, and a mask, especially when using chemical solutions. Ensure the area is well-ventilated.

Method 1: Boiling Water

For a chemical-free approach, boiling water can be effective in removing lichen from concrete. The high temperature helps to kill the lichen and loosen its grip on the concrete.

  1. Boil Water: Bring a large pot of water to a boil.
  2. Pour Over Lichen: Carefully pour the boiling water over the lichen-covered areas. Be cautious of splashing.
  3. Scrub and Rinse: After allowing the water to sit for a few minutes, use a stiff brush to scrub the lichen off the concrete. Rinse the area with clean water.

Method 2: Vinegar Solution

Vinegar is a mild acid that can kill lichen and help remove it from concrete surfaces.

  1. Prepare Solution: Mix white vinegar with water in a 1:1 ratio in a spray bottle.
  2. Apply to Lichen: Spray the solution generously over the lichen and let it sit for about an hour.
  3. Scrub and Rinse: Use a stiff brush to scrub the area thoroughly, then rinse with clean water.

Method 3: Commercial Cleaners

There are commercial cleaners specifically designed to remove lichen from concrete and other outdoor surfaces. Follow the manufacturer's instructions carefully.

  1. Choose a Cleaner: Select a cleaner suitable for concrete and effective against lichen. (usually sodium hypochlorite)
  2. Apply as Directed: Typically, you'll need to dilute the cleaner with water and apply it to the affected area.
  3. Wait, Scrub, and Rinse: Allow the cleaner to work on the lichen for the recommended time, then scrub with a stiff brush and rinse the area thoroughly.

Method 4: Pressure Washing

For larger areas or stubborn lichen, a pressure washer can be highly effective. However, use caution to avoid damaging the concrete.

  1. Set Up Pressure Washer: Use a pressure setting to prevent damage.
  2. Pressure Wash the Area: Move the washer nozzle evenly over the lichen-covered areas to remove the growth.
  3. Rinse and Repeat if Necessary: Rinse the area with clean water. Repeat the process if some lichen remains.
  4. Post treat solution: Usually apply a solution of half and half pool chlorine to ensure the result will last. Take care of plants and yourself using these chemicals.

Preventing Lichen Growth

Prevention is key to ensuring lichen doesn't return. Improve drainage and sunlight exposure to the concrete area and consider applying a sealant designed to prevent organic growth.


Removing lichen from concrete requires patience and the right approach. Whether you choose a natural method, or a commercial cleaner, regular maintenance and preventive measures will keep your concrete surfaces lichen-free and looking their best.