Moss is a non-vascular plant that commonly appears as a dense, green, carpet-like growth on hardscapes like patios and walkways. Its presence on pavers indicates underlying moisture issues and can create slippery surfaces that pose a hazard. Removing this growth requires a dual approach: immediate elimination followed by long-term environmental management. This guide provides methods to clean your paved surfaces and establish conditions that discourage moss from returning.
Why Moss Thrives on Pavers
Moss relies on small, hair-like structures called rhizoids for attachment, thriving on surface moisture rather than soil nutrients. Pavers provide an ideal environment because their porous nature, especially concrete or brick, retains water for extended periods. The small gaps between stones collect organic debris and dust, creating a slightly acidic growing medium.
Shade is another major factor, preventing the sun from quickly evaporating surface water and keeping the pavers damp. Poor drainage, which leads to water pooling, further contributes to the moist conditions moss requires. A combination of consistent moisture, limited sunlight, and accumulated organic matter creates the perfect habitat for moss spores to flourish.
Mechanical Removal Methods
Mechanical methods offer an immediate solution to moss infestation without introducing chemicals to the environment. For light or newly established moss, a simple stiff-bristled broom or brush can be highly effective in dislodging the plant from the paver surface and joints. Specialized joint scrapers or wire brushes can be used to carefully dig into the narrow gaps, ensuring the rhizoids are thoroughly removed to prevent rapid regrowth. It is important to perform this task when the pavers are dry, as the joint sand will be firm and less likely to be disturbed.
For heavy moss buildup, a pressure washer provides the most efficient and powerful removal option. To prevent damage to the pavers or the jointing material, it is recommended to use a machine with a pressure setting between 1000 and 1500 pounds per square inch (PSI). The nozzle should be held at least 12 to 18 inches away from the surface and aimed at a 45-degree angle, using a fan tip. This process will inevitably wash away the sand between the pavers, making it necessary to sweep fresh joint sand into the gaps once the area is completely dry.
Chemical and Natural Treatment Solutions
Chemical treatments are effective for killing moss and often involve commercial products or common household agents.
Commercial Treatments
Many specialized moss-killing products use ammoniated soaps of fatty acids, which work by disrupting the moss cell membranes, causing them to dry out quickly. Zinc sulfate monohydrate is a non-staining commercial option highly effective against moss on hard surfaces. Iron-based moss killers should be avoided on pavers as they can leave rust-like stains on the stone surface.
Household Solutions
Household solutions provide accessible alternatives that can be mixed at home. A white vinegar solution, typically mixed with equal parts water, can be sprayed directly onto the moss, where its acidity helps break down the plant. Common household bleach can also be diluted with water, often at a 1:3 ratio, and applied to affected areas. When using bleach, protect nearby vegetation with a thorough pre-wetting or covering, and rinse the treated area completely after 15 to 30 minutes to prevent surface damage.
Application and Cleanup
Another natural option is creating a paste using baking soda and water, which raises the surface pH and dehydrates the moss. Regardless of the agent used, personal protective equipment, including safety goggles and gloves, should be worn during application. The dead moss must then be scrubbed away with a stiff brush, and the entire area thoroughly flushed with clean water to remove all residue and prevent staining or harm to the surrounding landscape.
Stopping Future Moss Regrowth
Preventing moss from returning requires addressing the underlying environmental factors that allow it to thrive. The primary goal is to minimize moisture retention and increase sunlight exposure across the paved area.
Preventative Measures
Several strategies help manage the environment to discourage regrowth:
- Trimming back overhanging trees or dense shrubs allows more light and airflow to reach the pavers, helping the surface dry out faster after rain.
- Improving drainage is important, especially where water tends to pool, which may involve adjusting the patio grade or cleaning out nearby gutters.
- Applying polymeric sand is a highly effective preventative step once the joints are clean. This specialized sand hardens when activated by water, creating a dense, solid barrier in the paver joints.
- Applying a high-quality paver sealant is an excellent long-term strategy. Sealants penetrate the porous material, reducing its ability to absorb and retain moisture.
Pavers should be completely clean and dry before sealant application. Choosing a product specifically formulated with moss and algae resistance will offer the best defense against future organic growth.