How to Clean Patio Stones and Remove Moss
Interlock patio stones and natural stone patios develop moss, lichen, and algae growth in shaded or consistently damp areas — particularly in Toronto's climate, which provides sufficient moisture. These growths make surfaces slippery and aesthetically unappealing. Cleaning methods range from manual removal to chemical treatment.
Method 1: Bleach Solution (Most Effective for Moss and Algae)
- Mix 1 part household bleach with 10 parts water in a garden sprayer or bucket
- Wet the patio stones first with water
- Apply the bleach solution to all affected areas
- Allow 20–30 minutes — the bleach kills the moss, algae, and lichen
- Scrub with a stiff deck brush to loosen the dead growth
- Rinse thoroughly with a garden hose — bleach must be fully rinsed off patio areas to protect surrounding plants and soil
- The dead growth will continue to weather away over the following weeks
Method 2: Pressure Washing (For Dirt and Grime)
- A pressure washer with a fan-tip nozzle on 1,500–2,500 PSI is effective for removing loose moss, algae, and dirt from patio stones
- Work systematically in one direction
- Note: pressure washing loosens joint sand in interlock patios — plan to re-sand the joints after washing
- For established moss: bleach treatment first, then pressure wash after the growth is dead — much more effective than pressure washing live moss
Method 3: White Vinegar (For Light Growth, Eco-Friendly)
- Spray undiluted white vinegar on affected areas
- Allow 1 hour
- Scrub with a stiff brush and rinse
- Less effective than bleach for established growth but safe for use around plants and grass
Prevention
- Polymeric joint sand in interlock joints reduces the spaces where moss takes hold
- Improving drainage under and around the patio reduces the persistent moisture that enables moss growth
- Trimming overhanging branches increases sunlight — most moss growth occurs in shade
Book a Maidless deep clean at maidless.ca — 4.9★, 100+ reviews, vetted cleaners across Toronto.