How to Clean a Flagstone or Bluestone Patio

A flagstone or bluestone patio adds functionality and beauty to a home landscape, so maintaining your patio pays multiple rewards. Sweeping or blowing leaves, dirt and debris off your patio is all it takes to keep your patio looking good most of the time. But sometimes it is necessary to do a more intensive cleaning job. The first step in cleaning a soiled or stained patio begins with assessing the nature of the dirt or stains.

Sweep your patio with a natural- or plastic-bristle brush or use a leaf blower to remove loose dirt and debris.

Attach a jet spray nozzle to your garden hose and wash down the patio with clear water.

Inspect your patio for remaining dirt or stains.

Embedded dirt requires a more intense cleaning. The best products to use depend upon the need.

Natural- or plastic-bristle broom

Garden hose

Jet-spray hose nozzle

Large bucket

Neutral-pH stone-cleaning product

Measuring cup

Mop

Mix 1 to 4 ounces of a neutral-pH stone cleaner per gallon of water or whatever ratio the manufacturer suggests. For large patios, mix several gallons of the solution in a large bucket.

Mop the solution onto the pavers.

Clean patios on cool or overcast days to prevent rapid evaporation of the cleaning solution. 

Do not allow cleaning solution to dry on the pavers.

Clean large patios in sections.

Wait for two minutes before you scrub the pavers, giving the solution time to loosen dirt and stains.

With a natural- or plastic-bristle brush, scrub the pavers. Agitate the brush to loosen dirt and stains.

Using your jet-spray nozzle on your hose, water-sweep the solution off the pavers.

Use a clean mop or wet vacuum cleaner to remove excess water.

Hydrogen peroxide or household ammonia

Stone poultice

Small disposable plastic container

Distilled water

Plastic spoon

Plastic wrap

Painter's tape

Plastic or wooden scraper

Soft cloth

Mop

Wet vacuum cleaner, optional

Add 1/2 cup of hydrogen peroxide or household ammonia to 1 gallon of water to remove biological stains such as algae, mildew or moss.

Mop the solution onto the affected area and allow it to soak for several minutes before scrubbing with a natural- or plastic-bristle brush.

Rinse the cleaning solution off the pavers with a jet-spray nozzle on your hose. Use a clean mop or wet vacuum cleaner to remove excess water.

Stains are foreign matter absorbed into the stone. Removal of the stain is a reverse process, pulling the foreign matter out of the stone.

Put poultice powder in a small, disposable plastic container and add enough distilled water to make a thick, spreadable paste, stirring with a plastic spoon and carefully following manufacturer's instructions.

Wet the stained area and 2 to 3 inches beyond the stain with distilled water, then spread the poultice paste 1/4- to 1/2-inch thick on the wet area.

Cover the poulticed area with plastic wrap and tape the edges of the plastic to the pavers. Leave the poultice in place for 24 to 48 hours.

Remove the plastic wrap and allow the poultice to dry completely before scraping the poultice material off the flagstones. Rinse the treated area with distilled water and wipe dry with a soft cloth.

Repeat the poultice treatment if the stain is not completely removed. 

Persistent stains may require professional treatment. Consult a local stone professional for advice if you are not able to remove a stain yourself.