Conquer Concrete Stains Once and for All with Wet & Forget Outdoor!

Wet & Forget cleans sidewalks

Concrete is a durable, attractive and long-lasting option for constructing everything from driveways, to patios, to pool surrounds. But when disgusting mold and mildew, green or black algae, lichen or moss invade the areas around your home, your concrete surfaces can turn from assets to expensive eyesores.

You don’t need to turn to caustic chemicals or pressure washing to make these ugly stains disappear, though. With Wet & Forget Outdoor, just spray and walk away to defeat these growths and keep them from coming back for a year or more in most cases.

No elbow grease needed! Continue reading to see how.

Green or black algae, mold and mildew, lichen, and moss can all grow on your outdoor concrete surfaces. These ugly growths spoil the appearance of your concrete, and some growths can even cause damage.

Growths such as green algae, mold and mildew can cause concrete sidewalks, driveways or patios to become extremely slippery, creating a fall risk for you and your family.

If you’ve tried to remove these growths using bleach or pressure washing, you may have run into problems. Bleach can ruin your clothes and other fabrics, irritate your skin, eyes and airway, and kill your lawn.

Pressure washing is a hassle that can leave behind a muddy mess, and can cause any loose pieces of concrete to break off. To make matters worse, the growths you’re trying to get rid of can start forming again almost from the moment you finish cleaning, putting you in a frustrating cycle of cleaning and re-cleaning.

Break out of the cycle with Wet & Forget Outdoor. Wet & Forget’s gentle formula works with the wind and rain to remove algae, lichen, moss, mold and mildew over time, and keep them away for a year or more in most cases.

Wet & Forget Outdoor is safe to use on just about any outdoor surface, including concrete walls, patios, steps, driveways, sidewalks and pavers.  Plus, Wet & Forget won’t bleach your clothes or kill your lawn, either.

And there’s no scrubbing necessary–just spray the affected area and let Wet & Forget Outdoor do the work for you. It’s that simple!

Listen to this unsolicited testimonial from Dave L. that he left on the Wet & Forget corporate voicemail:


Here are the ugly stains that Wet & Forget erases:

Green algae likes to grow in shaded areas where there is moisture, such as the north side of your concrete retaining wall, or your concrete patio underneath the awning. It stains the concrete an unsightly dark to bright green, and can be very slippery.

If your concrete has ugly charcoal-gray or black streaks or splotches, black algae is probably the culprit. Black algae can grow on many outdoor surfaces such as concrete or roof shingles, and will thrive as long as there is moisture and sunlight.

Black algae has a pigmented protective capsule that gives it its dark color and also protects it from the sun, which is why black algae can live on areas that are exposed to even intense sunlight, such as exposed sidewalks and rooftops.

In the photo above, you can see just how much ugly staining black algae can cause on concrete–except at Joni D.’s house, that is. Joni treated her concrete driveway and sidewalks (circled in blue) with Wet & Forget Outdoor, and this aerial photo shows off her spectacular results.

Even pilots flying overhead can guess which family uses Wet & Forget!

Joni told us: “I didn’t realize how unbelievable the results were until my brother-in-law, who I had been raving about the product to, showed me a satellite shot of my house and neighborhood. My house had the only clean driveway and sidewalks in about a 6 block radius!”

  • Mold and Mildew

Mold and mildew thrive in shaded, damp areas. This disgusting fungal growth can be white, gray, brown or black in color, and produces a gross, musty odor.

In addition to concrete, mold and mildew also love to invade the cushions on your outdoor furniture.


  • Lichen

Lichen is a stubborn, multi-layered growth than can form on almost any outdoor surface, even glass. It has a scaly texture and comes in a wide variety of colors, including green, reddish, bluish and bright yellow. Lichen is very hardy and can be difficult to remove.

  • Moss

Moss is a green, carpet-like simple plant. It grows in moist areas, and can form in any cracks your concrete might have. Then, as it grows, moss can cause the cracks to get bigger, shortening the life of your concrete surface. This makes moss much more than just an ugly nuisance.

How to Apply Wet & Forget Outdoor

Wet & Forget Outdoor will tackle all of these ugly stains on your concrete, with no elbow grease required. Here are the steps to get rid of these growths once and for all:

  1. Mix 1 part Wet & Forget with 5 parts water in a pump-up garden sprayer.
  2. Spray the affected concrete with the diluted Wet & Forget solution.
  3. Allow at least 4 to 5 hours of drying time before the chance of rain.
  4. Walk away, and let Wet & Forget Outdoor do the work for you!
  5. Re-apply yearly or at the first sign of re-growth to keep the stains away for good.

For moss, be sure to saturate thoroughly so that the solution can reach the root-like structures. Follow these special instructions to remove lichen.

Stop by our website to learn more about our easy solutions to everyday problems, so you can spend less time cleaning and more time enjoying life!


    1. Hi Barbara,

      It’s not recommended to apply Wet & Forget with gloves + sponge. For best results use a garden pump sprayer because you’ll be able to completely saturate the stone and it’ll be much easier to apply. What I would do is fill up the sprayer with Wet & Forget and water and bring it to the cemetery. Spray the stone, apply heavy and leave it to dry. When the rain hits the surface it’ll reactivate the product to gently breakdown and remove the growth.

      — If there is lichen on the stone, apply Wet & Forget and then wait 15 minutes. Then re-apply to the lichen. During the 15 minutes the lichen with actually open-up and expose it’s roots so the second application will be able to get into the growth’s root system.

      Thanks for commenting

  1. Which product would I use to clean stains from the concrete deck and edging of an indoor swimming pool? Would there be any changes in application for this? Can it be used under rubber mats on the pool deck?

    1. Hi Barbara,

      You would want to use Wet & Forget Outdoor, it’s safe for any exterior surface including your deck, rubber mats, and the edging of a pool. Be sure to completely saturate the surface and leave and let dry. Each time it rains it will re-activate the product to gently breakdown the growth and remove it.

      For the edging of pools, you want to drain to the level of the stain and let dry, then apply Wet & Forget and let it completely dry. The next day fill your pool back up and that’s it.

      Unfortunately Wet & Forget is only registered to use on exterior surfaces so I cannot recommend using on a pool that is indoors, however if it’s enclosed in an outdoor screen patio you’re totally fine. Thanks for commenting.

    2. We are in SW Florida and we are faced with power washing our driveway and sea wall because they always turn black. You recommend a yearly application with this product. Will we need to power wash again before reapplying?

      1. Hi Penny,
        You do not need to power wash before reapplying Wet & Forget. However, per our labeling we do not recommend using Wet & Forget with-in 100 feet from any pond, lake, stream, or river.

  2. All rain runoff from my moldy driveway will go through a flower bed planted with perennial plants and bushes. How will Wet & Forget affect them, please?

    1. Hi Mary,

      The runoff of your application from rainfall will not have an effect on your flower bed.

      During the application you don’t want to directly spray your plants with Wet & Forget, it will not get into the root system of your flowers though it can turn the petals brown and spotty. To avoid this, you can spray your plants with water before and after the application.

    1. Hi Jean,

      Wet & Forget only removes organic growth such as moss, mold, mildew, or algae. If the stains on your surface do not wash off with soap and water, chances are it’s a growth. Let me know if you have any other questions.

  3. Would this work on a concrete outxoor fountain to help remove green algae stains?

    We have a 10 gallon fountain that has severe green algae stains. I’ve tried to remove the stains with bleach, but it still leaves discoloration in the fountain.

    1. Hi Darlene,

      Wet & Forget will remove the green algae stains in your concrete outdoor fountain. For best results, drain your fountain and let it dry out. Next, apply a heavy coat of Wet & Forget and allow it to dry. The next day refill your fountain and turn it back on and that’s it.

  4. Is wet and forget safe to use outdoors in pet traffic areas?
    Should I keep pets off of treated ares for a specified amount of time?

    1. Hi Cherylan,

      Wet & Forget is safe to apply to areas around the house where pets may walk. During the application while the surface is still wet, keep pets off the area. Once the surface has completely dried, pets are fine to walk on the area.

  5. I have a Nylon canopy over my deck. Will Wet and forget ruin the stitching in the canopy. The real question should be “is it safe on cloth or cotton stitching?

    1. Wet & Forget is safe to use on your nylon canopy to remove any moss, mold, mildew, or algae that’s on the surface. Wet & Forget will not damage the cloth or cotton stitching. Here’s a link to one of our other blog posts with a Wet & Forget customer’s experience using Wet & Forget on their awnings: Wet And Forget Awnings.

  6. I am researching your product for keeping green mold off a concrete sidewalk. will this product prevent mold from growing? if so, for how long? does this come with a warranty? if so, for how long?

    1. Wet & Forget Moss Mold Mildew And Algae Stain Remover is going to properly clean the surface, because of this we typically see surfaces remaining clean for at least 12 months. In our home state of Illinois, we can apply once every year to two years depending on how rainy the seasons were. If you’re in an area similar to Florida where rain is heavy and more common, you will definitely see regrowth happen much quicker.


    1. Hi Patty,
      Yes, Wet & Forget will restore the look of dirty pebble stone patios and sidewalks. Apply to both surfaces and leave your application to the wind and the rain for all the rinsing and scrubbing.

    1. Hi Toni,
      Yes, Wet & Forget is safe to use to clean up outdoor bamboo shades as well as virtually any other outdoor surface you’re going to get green algae and black mold stains on.

  8. Will Wet And Forget work if no rain can hit the area? My mold or black algae is growing under an area that does not get wet. Would I need to rinse it off after so much time or does it need rain water to work?

    1. Hi Bobbi,
      Yes, Wet & Forget will still work on surfaces that are not exposed to the rain, but you’ll need to help along the process. First apply a good heavy amount of Wet & Forget to the dry surface and leave it. I would wait about a week and then periodically you can take a hose on a jet setting and rinse the area to help remove the dead growth.

  9. I hAve a question about cold weAther APPLICATION. How cold is too cold? I would like to clean my driveway early this spring. I live in northern oregon and spring can be wet and cold.

  10. can the product be used near a pool? We are hoping to use it to clean our pool deck. We have a new vinyl liner and don’t want any chemicals that could affect it. we don’t intend to have any get into the pool – but because we will be cleaning near it, some could seep in if it rained.

    1. Hi Brian,
      Our product is safe to use around the pool. If any over spray gets into the pool, it will not harm the pool water.

  11. I just applied what and forget to my patio. How long does it take before you start seeing some results. Do I need to hose off the patio if I do not have rain within a few days?

    1. Hi JT,
      If you have green growth on the surface you can start to see results 1-2 weeks after your initial application. If you have black growth on the surface you can start to see results 1-2 months after your initial application. If you’re not seeing a lot of rain in your area, you can rinse the surface with a hose on a jet setting to help speed up the cleaning process about a week after your application.

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