How to Remove Lichen From Roof Tiles and Outdoor Surfaces

How to Remove Lichen From Roof Tiles and Outdoor Surfaces

There’s nothing to like about lichen- especially when it invades on your home’s outdoor surfaces.

This ugly growth spreads across roofs, walls, and sidewalks with strands or “fingers” holding on with a powerful grip.

Here’s the lowdown on lichen and how to kick it to the curb with Wet & Forget Outdoor.

What is lichen?

Lichen is a combination of algae and fungus.

Roofs, pavers, rock walls, gravestones, and sidewalks are popular areas where lichen can be found. Although, they can be found on virtually any outdoor surface.

Lichen is an invasive organism and may appear on surfaces as tiny, shrubby branches (fruticose) leafy structures (foliose), or in crusty patches (crustose). Lichens thrive on a combination of sunlight, carbon dioxide, water, and minerals.

What are the most common types of lichen?

One of the most common types of lichen is made up of single-celled green algae (Trebouxia). This type of lichen can be found growing worldwide in temperate, alpine, and arctic regions worldwide.

Lichen can grow in a wide range of temperatures and conditions; from the hottest desert to the coldest arctic tundra.

What does lichen look like?

Lichens come in multiple shapes, sizes, and forms including shrubby, leaf-like, or crusty. It may appear as an orange crust on a rock wall, or as mint green patches on a roof.

Lichen can be seen in a variety of colors including blue-green, gray, brown, and yellow.

lichen on stone

Is it harmful? Should I remove it?

While lichen may appear to be harmless it can cause significant damage to outdoor surfaces over time.  This can shorten the life of your roof or other outdoor surfaces.

This surface moisture may freeze in cold weather and cause frost damage to asphalt shingles or other surfaces. Lichen holds moisture against the surface thus speeding up the wear and tear. So over time, your roof shingles may bend and warp.

The lichen can also penetrate your roof’s exterior causing the shingles to separate and spell disaster for your roof!

Another reason to remove lichen growth is your homeowner’s insurance rates may increase. Your insurance company may send out an inspector to drive by your home to observe any changes.

If the inspector sees a dirty, lichen-covered roof, this may give them a reason to raise your rates or even cancel your policy because lichen can cause serious damage over time.

Fortunately, it can easily be removed with Wet & Forget Outdoor.

lichen roof

How do I get rid of lichen?

The problem with scraping, sweeping and raking

Removing lichen with a brush, broom or scraper is one common way to remove it. Unfortunately, removing lichen this way is very time and labor-intensive.

Lichen can be really tricky to remove because it grips strongly onto the surface. So if you attempt to remove it with a hand tool, you may accidentally remove the protective top layer of your roof shingles as well.

Using metal strips

Lichen avoids galvanized steel, copper, and zinc because these metals work as a natural biocide. Adding metal strips along your roof’s ridge line may inhibit lichen growth.

When rainwater moistens the strips a tiny amount of metal will run down on your roof preventing the lichen from grabbing hold. Unfortunately, copper and zinc dripping from your roof is bad for the environment.

The runoff will find its way into streams and ponds where it is toxic to fish and other wildlife. Metal-infused rainwater is also unsuitable for landscape use.

Chlorine bleach

Although it’s an inexpensive option to remove lichen from your roof, the end result may corrode downspouts, gutters, and flashings. True to its name, chlorine bleach may “bleach” your asphalt shingles, lightening or changing the color.

Bleach solution that drips from your roof during or after application can kill landscape plants and ruin outdoor fabrics. You may need to wear protective clothing when applying bleach as the solution can burn the skin.

The bottom line is bleach can be hazardous to people and the environment.


Since pressure-washing can degrade your roof’s protective coating, it is not a recommended method for removing lichen.

It can also compromise the seals around windows and doors and damage skylights and roof windows. Also, mold growth can occur underneath your home’s siding and get into the inner walls from a forced water source.

Keep in mind- some shingle manufacturers will void the warranty on their products if they discover that you have subjected your roof to high-pressure washing. So, be sure to reach out to your shingle manufacturer before treating your roof.

lichen on wood
Why is Wet & Forget Outdoor the Best Way to Remove Lichen?

Wet & Forget Outdoor’s gentle, eco-friendly formula kills lichen without damaging your outdoor surfaces. It does so by working with the wind and rain to remove the unsightly lichen.

And Wet & Forget Outdoor keeps on working to keep outdoor surfaces clean and lichen-free for months!

Two applications of Wet & Forget is required to thoroughly treat and eliminate lichen.

How to Apply Wet & Forget Outdoor
  1. Make sure no rain is in the forecast that day.
  2. Dilute 1 part Wet & Forget Outdoor to 5 parts water in a pump-up garden sprayer.
  3. Once diluted, thoroughly saturate the lichen or moss-covered surface.
  4. Then wait 15 minutes before repeating step 2.
  5. After the second application, allow the surface to dry for 4 to 5 hours.

To make one gallon of the solution:

Begin by adding 2 1/2 cups (20 oz.) of Wet & Forget Outdoor to your garden sprayer. Then, add water to your garden sprayer until the one-gallon mark.

To make two gallons of the solution:

Start by adding 5 cups (40 oz.) of Wet & Forget Outdoor to your garden sprayer. Then, add water to your garden sprayer until the two-gallon mark.

Listen to this unsolicited testimonial from Dave L. that was left on Wet & Forget’s corporate voicemail:

wet forget cleaner headstones


Surface Preparation

For best results apply Wet & Forget Outdoor to a dry surface.

Before spraying the surface, remove any loose debris. Completely saturate the surface with Wet & Forget Outdoor to penetrate the growth.

Ideal Temperatures for Application

During the application process, check to make sure that the temperature is above 32°F (0°C) for the best results.

Then, allow it to dry for 4 to 5 hours after the application.

Ideal Weather

For best results apply Wet & Forget Outdoor on a cool, dry day. Early morning or later in the evening are the most ideal times to apply Wet & Forget Outdoor.

This will ensure that the surface will remain wet for an extended period of time and allow it the optimum time to do its job.

Future Maintenance

When the stains and growth have finally disappeared, use Wet & Forget Outdoor as a routine maintenance tool to keep your surfaces clean and lichen-free. In the future, apply it annually or if the growth reemerges to keep the stains away.

Cleaning Vertical or Covered Surfaces

Vertical surfaces or surfaces without exposure to natural elements like covered porches and headstones may require some assistance with a hose or a scrub brush. If the area is heavily stained, a yearly application of Wet & Forget Outdoor will keep surfaces clean.

Eliminating lichen is easy with Wet & Forget Outdoor. Plus, there is no hand raking or scaping required.

Don’t let the disgustingly dirty outdoor surface ruin your summer day.

Wet & Forget Outdoor will make your outdoor living areas shine like new!


  1. Jacquie coble

    Can this product be used on the sand in a childs sandBox? If so how should i apply it?

    1. Wet And Forget

      Hi Jacquie,
      Wet & Forget can be used on the sandbox but we wouldn’t recommend applying to the sand. I would follow the directions on the bottle for children’s play equipment.

  2. Scott jenkins

    Can Wet And Forget be used on cedar shake shingles?

    1. Wet And Forget

      Hi Scott,
      Absolutely! Wet & Forget is safe and effective for cleaning cedar shake shingles. For best results, apply a good heavy amount to the surface and then just allow the wind and the rain to do the cleaning for you.

  3. Debbie Edgar

    Will Wet And Forget remove calcium deposits on pool tile and moss rock?

    1. Wet And Forget

      Hi Debbie,
      Wet & Forget will remove the moss on your rocks, but it won’t clean calcium deposits on pool tiles.

  4. Brent

    I have grayish colored lichens on a painted metal roof on older house trailer-cottage. Can I use this product safely on the white painted steel roof and the white painted sides. Roof is most likely galvanized steel while sides are most likely aluminum.

    1. Wet And Forget

      Hi Brent,
      You can definitely use Wet & Forget to take care of the lichen that is on your painted metal roof. Wet & Forget is safe to use on all types of roofs including both painted and metal surfaces.

  5. Terry A Johnston

    You seem to discourage the use of a high pressure washer, but would it be okay to use Wet And Forget in a high pressure washer using a wide angle nozzle? There is no way I can apply to my chimney or roof with a garden pump sprayer.

    1. Wet And Forget

      Hi Terry,
      You can use Wet & Forget with a pressure washer, but you must be able to pull from a larger premixed tank, rather than using water from a hose connected to your home. A pressure washer will not properly mix Wet & Forget, so pulling from a premixed tank is the only workaround. You can also use a Trombone Sprayer to apply Wet & Forget from a large distance away.

      1. henry mclaughlin

        can I use a Ortho Dial N Spray hose end sprayer and get the right mix of Wet and Forget?

        1. Wet and Forget

          Hi Henry,
          We do not recommend using a hose end sprayer with Wet & Forget as it will dilute our product too much. We recommend applying with a garden pump sprayer or a backpack sprayer using our 1 part Wet & Forget to 5 parts water mixing ratio.

  6. Kevin Carney

    My shingles are weathered grey. Will wet and forget change the weathered grey look of the shingle like bleach or would it stay a weathered grey color?

    1. Wet and Forget

      Hi Kevin,
      Our product will not change the weathered grey look of your shingles. Wet & Forget does not contain any bleach and will not harm the weathered grey color of your shingles.

  7. Fiona Cole

    Can you use wet and forget on a clear polycarboante pergola roof?/

    1. Wet and Forget

      Hi Fiona,
      Wet & Forget is safe to use on a clear polycarbonate pergola roof.

  8. gavin

    Can this be used with lead lettering on a marble gravestone? Not sure if it will react with the lead and stain the stone?

    1. Wet And Forget

      Hi Gavin, Wet & Forget is perfectly safe to use on marble gravestones that have lead lettering. No need to worry about any damage to the stone.

  9. Bob m

    Can wet and Forget be used on an IPE wood deck with cedar rails? Should I pressure wash first to remove some algae and lichen growth?

    1. Wet And Forget

      Hi Bob, Definitely use Wet & Forget on your IPE wood deck and cedar rails. I would apply Wet & Forget first and leave it. If you don’t want to wait on the rain and you would like to speed up the process, feel free to pressure wash about a week later.

  10. Al

    Can Wet and Forget be used with success to remove without scrubbing lichen from asbestos siding ?

    1. Wet and Forget

      Hi Al,

      Yes, you can use Wet & Forget to remove lichen that is on your asbestos siding without scrubbing. However, there is a second step that you need to follow when applying to surfaces that have lichen on it. After you apply the Wet & Forget to the surface, wait 15 minutes and then apply a second time.

  11. Hank Miraldi

    Have shingled roof on garage with a fair amount of large circular lichen attached. These small circle shaped lichen come off with very little effort. Should I remove them before applying product?

    1. Wet and Forget

      Hi Hank,
      It is not necessary to remove the lichen before applying Wet & Forget. However, if you want to help speed up the process of removing the lichen you can rinse your roof with water from a hose on a jet setting about a week after your application of Wet & Forget.

  12. Martin Friedburg

    Just picked up some Wet&Forget at Costco. O.K. to use on a brick & Mortar courtyard wall?


    1. Wet and Forget

      Hi Martin,
      Wet & Forget is safe to use on a brick and mortar courtyard wall.

  13. carlos

    Can wet and forget be used on canvas?

    1. Wet and Forget

      Hi Carlos,
      Wet & Forget can be used on canvas. Wet & Forget is a gentle product that works with the outdoor elements (rain/wind) to clean your surface.

  14. Liz

    Will Wet & forget damage garden plants?

    1. Wet and Forget

      Hi Liz,
      When applying Wet & Forget near plants, we recommend protecting all plants/grass from the overspray. You can do this by spraying the plants/grass with clear water before and after the application of Wet & Forget or you can cover the plants/grass when applying the Wet & Forget.

  15. SARAH

    Can you apply your product on trees to remove lichen? Lichen has started blooming all over my trees, fence, roof, everything!

    1. Wet and Forget

      Hi Sarah,

      You can use Wet & Forget to remove lichen from the trunk of trees. However, we recommend that you apply the Wet & Forget when the tree is in its dormant state, which is late fall. When applying to lichen, we also recommend applying Wet & Forget once to the surface, waiting 15 minutes, then completing a second application of Wet & Forget to get into the root system of the lichen.