Moss is a non-vascular plant that lacks a true root system. Instead, moss uses tiny thread-like structures called rhizoids to anchor itself to surfaces like paver stones. It thrives in environments that are persistently damp, heavily shaded, and often slightly acidic. Moss growth not only looks unsightly, but it also retains moisture, which can make the paver surface slippery and hazardous. Removing this persistent growth requires intentional methods, ranging from commercial chemical formulations to common household mixtures.
Chemical Agents for Moss Eradication
Commercial moss killers often utilize strong biocides designed to control or kill harmful organisms. One highly effective class of active ingredients is quaternary ammonium compounds, such as benzalkonium chloride. These compounds work by disrupting the cell membranes of the moss, causing the contents to leak out. Applying these specialized treatments typically involves a spray-on, “soft wash” approach that requires no immediate scrubbing.
Another potent, readily available chemical is household bleach, which contains sodium hypochlorite. Sodium hypochlorite acts as a strong oxidizer, rapidly breaking down the organic material of the moss. For effective use on pavers, dilute the bleach with water at a ratio of approximately 1 part bleach to 10 parts water. Applying this mixture requires caution, as overspray can easily discolor colored pavers or harm adjacent plants. The treated area must be thoroughly rinsed with clean water after the moss has been killed to remove all chemical residue.
Non-Toxic and Household Solutions
For a less aggressive or more environmentally conscious approach, several household items can effectively kill moss through changes in pH or dehydration. Distilled white vinegar, which contains acetic acid, is a common non-toxic option that kills moss by increasing the acidity of the paver surface. A mixture of equal parts vinegar and water (a 1:1 ratio) can be sprayed directly onto the moss, with a dwell time of 15 to 30 minutes before rinsing. For particularly stubborn patches, an undiluted application of vinegar is often necessary.
Baking soda, known as sodium bicarbonate, offers an alternative method by creating a highly alkaline environment hostile to moss growth. Since moss requires a slightly acidic to neutral pH, a shift toward alkalinity is lethal. The simplest application involves sprinkling a generous layer of dry baking soda directly over the damp moss and allowing it to sit for 24 to 48 hours. The dead, dried moss can then be swept away without needing a water rinse. A simple solution of water mixed with liquid dish soap can also be used, as the soap acts as a surfactant, helping the water penetrate the moss’s waxy cuticle to promote dehydration.
Essential Steps for Physical Removal and Cleanup
After applying a killing agent, physical removal is necessary to completely clear the dead moss and restore the paver surface. The initial step involves scrubbing the area with a stiff-bristle brush, which removes the bulk of the dead organic matter. For moss lodged deep within the joints and crevices, a narrow tool like a scraper or wire brush must be used to dislodge the rhizoids and dried remnants.
A pressure washer can dramatically speed up the cleaning process, but it requires careful use to prevent damage to the pavers or the jointing sand. The water pressure should be limited to approximately 1,500 pounds per square inch (PSI) or less. The nozzle should be held at a shallow angle and a safe distance from the surface. This controlled pressure removes debris without aggressively blasting away the joint sand that stabilizes the pavers. Following removal and cleaning, a final, thorough rinse with a garden hose is mandatory, especially after using chemicals, to flush away all residue.
Preventing Moss Regrowth
Effective long-term moss control relies on altering the environmental conditions that favor its growth. Since moss requires moisture and shade, increasing the amount of sunlight that reaches the pavers is beneficial. This can be achieved by trimming back overhanging tree branches or shrubs that cast shadows over the area. Any issues with standing water or poor surface drainage should be corrected, as eliminating sources of persistent dampness directly inhibits spore germination.
Applying a high-quality paver sealant is another proactive measure that contributes to prevention. Pavers are naturally porous, offering an ideal surface for moss spores to take hold and moisture to linger. A sealant fills these microscopic pores, creating a smoother, less hospitable surface that inhibits the attachment of spores. Additionally, ensuring that the paver joints are completely filled with jointing sand removes the deep crevices where moss often begins its colonization.