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The Home Depot

What Causes Patio Moss?

Pro Referral > Home Guides > Patio & Walkway > What Causes Patio Moss?
What Causes Patio Moss?

While trees and rocks covered with moss may be beautiful when they’re in a natural forest setting, moss on your patio is probably a different story. Although the layer of green isn’t necessarily unsightly, moss can create danger on a patio with its slick and slippery surface.


Before you take steps to remedy a moss-covered patio, visit the Oregon Metro website to learn about the causes of moss and different ways to manage it. Because moss does not grow with roots, it does not require the same growing conditions that standard plants need.


Once you know the causes of patio moss, you’ll be ready to remedy the issues and restore your patio to a clean and safe condition.

  1. Moss often appears on hard surfaces in shady and moist environments. Moss requires moisture to grow and reproduce.

    1.Moss Characteristics

    Moss often appears on hard surfaces in shady and moist environments. Moss requires moisture to grow and reproduce. Under the right conditions, moss can spread quickly to take over a patio surface.


    On a patio that has not received ongoing maintenance and cleaning, moss may develop and spread. It’s common for moss to grow over a patio surface where other organic matter exists, like leaves and weeds. Moss may also develop along the sand or material between paving stones.


    The main difference between moss and lichen and algae is the way they grow. Lichen and algae often penetrate a surface, whereas moss grows over the top of the surface.

  2. 2.Manual Removal of Moss

    Because moss sits on the surface of the patio or the materials between paving stones, an effective method for removal simply involves scraping or sweeping away the moss with broom or even a power washer. If you use a power washer, take care to ensure that you do not use a setting with enough strength to remove the jointing material between paving stones.

  3. 3.Chemical Removal of Moss

    Garden centers and home improvement stores carry a variety of different moss killing products. If you decide to proceed with a chemical removal product, read the ingredient label carefully first. Products that contain ferrous sulphate may produce an unsightly color change in your patio. This occurs because of a chemical reaction from iron in the product, producing a rust-like stain on the surface that may be difficult to remove.


    Instead, choose a moss killer that does not contain ferrous sulphate to ensure that you don’t cause staining on your patio surface as you remove the moss. Basic weed killers that contain glyphosate can be effective for moss removal. Chlorine bleach is another alternative that will kill moss and prevent it from returning on the patio surface.

  5. 4.Moss Prevention

    After removing the moss and restoring your patio, preventing the moss from returning requires only basic maintenance. Perform standard sweeping, hosing and brushing of the surface frequently. Once or twice each month, power wash your patio to ensure that it stays free of moss. If you notice moss trying to return, wash your patio down with a chlorine bleach solution once a month.


    With a diligent eye for preventing moss and basic patio maintenance, you should succeed in keeping your patio attractive and safe.

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