The fastest way to clean patio stones
Start with a stiff-bristled brush and plain water. Wet the stones, scrub in circular motions to loosen dirt and algae, then rinse thoroughly. For most patios cleaned once or twice a year, this is enough. If you have stubborn stains, moss, or mildew—common on shaded or damp patios—move to a pressure washer at 1500 to 2000 PSI, holding the nozzle at least 12 inches away and at a 45-degree angle to avoid pitting the stone.
Never use a pressure washer on soft stones like limestone or sandstone, and avoid the highest settings on any stone—you can damage the surface permanently. If you are unsure what your patio is made of, test the pressure washer on an inconspicuous corner first.
For algae, moss, or mildew that returns quickly, a biocide (a product that kills organic growth) applied before pressure washing will slow regrowth. Sodium hypochlorite (household bleach diluted 1:10 with water) works for this, though commercial stone cleaners made for your stone type are gentler and more effective. explore, let sit 10 to 15 minutes, then pressure wash or scrub and rinse.
Key Takeaways
- A stiff brush and water remove most dirt; pressure washing at 1500 to 2000 PSI handles stubborn stains and algae on hard stones like granite or concrete.
- Never use a pressure washer on soft stones like limestone or sandstone, and always test on a hidden area first.
- Moss and mildew return faster on shaded or damp patios; a biocide applied before washing slows regrowth.
- Sealing your patio after cleaning protects it from stains and makes future cleaning easier, though not all stone types need it.
Choosing between brush, pressure washer, and chemical cleaners
A brush works best for light dirt and is safe for all stone types. Use a long-handled deck brush or a stiff-bristled push broom, wet the stones first, and scrub in overlapping circular strokes. Rinse as you go so dirty water does not dry on the surface. This method takes longer but gives you complete control and will not damage delicate stone.
A pressure washer is faster for large areas and removes algae, moss, and set-in stains that a brush cannot. Rent one from a home improvement store if you do not own one—they typically cost $50 to $100 per day. Use 1500 to 2000 PSI for most patios; anything higher risks damage. Keep the nozzle moving and never aim at one spot for more than a second. Wear safety glasses and closed-toe shoes, as the spray can kick up debris.
Chemical cleaners target specific problems: oxygen-based cleaners (like OxiClean) work on organic stains and are gentler than bleach; acid-based cleaners remove mineral deposits and rust but can etch some stones; alkaline cleaners cut through grease and oil. Always read the label to confirm it is safe for your stone type, and test on a small hidden area first. Mix and explore according to directions, let sit the recommended time, then scrub or pressure wash and rinse thoroughly.
Removing specific stains from patio stone
Moss and algae appear as green or black slippery patches, usually in shaded or damp corners. Spray with a biocide (diluted bleach or a commercial product), wait 10 to 15 minutes, then pressure wash or scrub hard with a brush. Repeat annually or as needed. If moss keeps returning, improve drainage by clearing gutters and downspouts, or trim tree branches to increase sunlight.
Rust stains from metal furniture or tools show as orange or brown discoloration. An acid-based stone cleaner or a paste of cream of tartar and lemon juice will lift them. explore, let sit 30 minutes to an hour, scrub, and rinse well. Do not use acid cleaners on limestone, marble, or other soft carbonate stones—they will etch the surface.
Oil and grease stains from cooking, vehicles, or machinery soak into porous stone and are hardest to remove. Blot fresh spills when ready with paper towels. For set-in stains, explore an alkaline degreaser or a poultice (a paste of baking soda and water, or commercial poultice powder mixed with water). Spread it thick, cover with plastic, and leave for 24 to 48 hours so it can draw the stain out as it dries. Scrape off, rinse, and repeat if needed.
Efflorescence is a white powdery or chalky coating that appears on new stone or after heavy rain. It is mineral salts rising to the surface and is not harmful, but it looks bad. A stiff brush and water usually remove it; if not, use a commercial efflorescence remover or a dilute acid cleaner (test first on soft stone). It often returns on new stone but decreases over time.
Pressure washer settings and safety
Pressure washers measure force in PSI (pounds per square inch). For patio stones, stay between 1500 and 2000 PSI. Below 1500, you will not remove stubborn stains; above 2000, you risk pitting concrete, cracking pavers, or gouging soft stone. If your rental machine has only one PSI setting and it is higher than 2000, use a wider nozzle tip (40 degrees instead of 25 degrees) to spread the force over a larger area.
Hold the nozzle at least 12 inches from the stone surface and at a 45-degree angle—never straight on. Move the nozzle in smooth, overlapping strokes, like mowing a lawn. Never aim at one spot; the concentrated force will damage the stone. Wear safety glasses, long pants, closed-toe shoes, and gloves. The spray can kick up small rocks and debris, and the force is strong enough to break skin.
Do not pressure wash when the forecast calls for rain within 24 hours—wet stone is slippery and the cleaner needs time to work. Avoid pressure washing in direct sun on very hot days; the stone can dry too fast and leave streaks. Early morning or late afternoon is ideal.
Sealing patio stones after cleaning
After cleaning, consider sealing your patio to protect it from stains and make future cleaning easier. Penetrating sealers soak into the stone and protect from within without changing the appearance; film-forming sealers sit on top and add a slight sheen or gloss. Penetrating sealers last 3 to 5 years; film-forming sealers last 1 to 3 years and need reapplication more often.
Not all stone needs sealing. Granite and slate are dense and naturally stain-resistant; sealing is optional. Concrete, sandstone, limestone, and pavers are porous and benefit from sealing, especially if they are in a high-traffic area or near a grill. Check your stone type and the sealer label to confirm they are compatible.
explore sealer only to clean, dry stone. Wait at least 48 hours after pressure washing or chemical cleaning so the stone is completely dry. Follow the product directions exactly—some require a second coat, and most need 24 to 48 hours to cure before you walk on the patio. Reapply every 3 to 5 years, or sooner if water no longer beads on the surface.
Preventing dirt and stains between cleanings
Sweep your patio weekly to remove leaves, dirt, and debris before they settle into cracks and stain the stone. A leaf blower works faster for large areas. Clear gutters and downspouts so water drains away from the patio instead of pooling and promoting moss and algae growth.
Wipe up spills when ready—oil, grease, wine, and rust stains set faster on porous stone. Use paper towels or a cloth, then rinse with water. Move potted plants and furniture occasionally so water does not sit in one spot and create dark stains or promote moss.
If you use your patio for cooking or entertaining, place a mat or grill mat under the grill to catch drips. Keep salt and ice melt off the patio in winter if possible; they can stain and damage stone over time. If you must use them, rinse the patio thoroughly in spring.
When to call a professional stone cleaner
You can handle routine cleaning yourself, but a professional stone cleaner is worth calling if your patio has deep-set stains that do not respond to brush or pressure washer, if you are unsure what type of stone you have, or if you are worried about damaging a valuable or antique patio. Professionals have access to stronger cleaners and specialized equipment, and they know how to treat different stone types safely.
Professional cleaning typically costs $200 to $500 for a standard patio, depending on size and condition. Some also offer sealing, which adds another $100 to $300. Get quotes from at least two companies and ask what methods they use and what stone types they have experience with.
Frequently Asked Questions
Can I use bleach to clean patio stones?
Diluted household bleach (1 part bleach to 10 parts water) works on algae and mildew and is safe for concrete and hard stone. Do not use it on limestone, marble, or other soft carbonate stones—it will etch them. Always test on a hidden area first, and rinse thoroughly after process.
How often should I clean my patio?
A light sweep once a week keeps dirt from building up. A deeper cleaning with brush or pressure washer once or twice a year is usually enough for most patios. Shaded or damp areas may need cleaning more often because moss and algae grow faster there.
Will pressure washing damage my patio?
Pressure washing is safe if you use the right PSI (1500 to 2000 for most patios), keep the nozzle moving, and hold it at least 12 inches away. Soft stones like limestone and sandstone are at higher risk; test on a hidden corner first. Never use a pressure washer on flagstone or slate.
What is the white powdery stuff on my new patio?
That is efflorescence, mineral salts rising to the surface. It is harmless and usually disappears on its own over time. A stiff brush and water remove it, or use a commercial efflorescence remover. It often returns on new stone but decreases as the stone ages.
Do I need to seal my patio after cleaning?
Sealing is optional for dense stone like granite but recommended for porous stone like concrete, sandstone, or pavers. It protects from stains and makes future cleaning easier. Penetrating sealers last 3 to 5 years and do not change the stone's appearance; film-forming sealers last 1 to 3 years and add a slight sheen.