Bluestone cleans best with a soft brush, mild detergent, and water—never pressure washers or acidic cleaners

Bluestone is a sedimentary rock that stains easily and breaks down under high pressure or harsh chemicals. The safest method is a soft-bristled brush with a mixture of warm water and a small amount of dish soap, followed by a thorough rinse. This removes dirt, algae, and light stains without etching the surface or forcing water into the stone's pores, which can cause spalling (flaking) over time.

Bluestone's natural texture and color make it attractive, but that same texture traps dirt and allows moss and algae to grow in shaded areas. Cleaning every season—or more often in damp climates—keeps the patio looking fresh and prevents buildup that becomes harder to remove. The entire process takes one to three hours depending on patio size and how dirty it is.

Key Takeaways

  • Never use a pressure washer on bluestone; the force can crack the stone and force water into its pores, causing damage months later.
  • Soft-bristled brushes, warm water, and dish soap remove most dirt and algae without harming the stone surface.
  • Avoid acidic cleaners like vinegar and muriatic acid, which etch bluestone and leave permanent dull spots.
  • Rinse thoroughly after cleaning to remove all soap residue, which can leave a film and attract more dirt.
  • Seal bluestone every two to three years after cleaning to reduce staining and make future cleaning easier.

Gather your supplies before you start

You will need a soft-bristled brush (not a wire brush), a bucket, warm water, a small amount of dish soap, and a garden hose with a spray nozzle set to a gentle mist. Do not use a pressure washer, even on the lowest setting. If you have stubborn stains, keep a bottle of oxygen-based cleaner on hand—this type breaks down stains without etching the stone, unlike vinegar or bleach.

Wear gloves to protect your hands and consider wearing old clothes, since wet stone can be slippery. If your patio is large or heavily soiled, you may want to rent a soft-bristled deck brush on a long handle to reduce bending. Check the weather forecast and plan to clean on a day when rain is not expected for at least a few hours afterward.

Remove loose dirt and debris first

Sweep the entire patio with a regular broom to remove leaves, twigs, and loose dirt. This step prevents you from grinding grit into the stone when you scrub. Pay special attention to corners and the spaces between pavers, where debris collects and traps moisture.

If moss or algae is thick, let it dry completely, then brush it away with a stiff (but still soft) brush before you wet the stone. Wet moss is slippery and harder to remove; dry moss brushes off more easily. This dry-brushing step can remove 30 to 50 percent of the algae without using any water or soap.

Mix and explore your cleaning solution

Fill a bucket with warm water and add one to two tablespoons of dish soap per gallon. Stir gently to mix. This concentration is strong enough to cut through dirt and algae but mild enough not to damage the stone. Do not use laundry detergent, which contains additives that can leave residue, and do not use bleach, which can discolor bluestone over time.

Dip your soft-bristled brush into the solution and scrub the patio in the direction of the stone's grain (if visible) or in overlapping circular motions. Work in small sections—about 4 by 4 feet at a time—so the soap does not dry before you rinse. Pay extra attention to areas where algae or moss is visible, and scrub grout lines between pavers thoroughly.

Rinse thoroughly with clean water

Once you have scrubbed a section, rinse it when ready with your garden hose set to a gentle spray. Do not use a high-pressure nozzle; keep the spray soft and even. Rinse until the water runs clear and you see no soap bubbles. Leftover soap residue will attract dirt and can leave a dull film on the stone.

Move to the next section and repeat the scrub-and-rinse process until the entire patio is clean. This may take several passes if the patio is very dirty. Once you have finished the whole patio, do a final overall rinse to catch any soap you may have missed.

Treat stubborn stains with oxygen-based cleaner

If soap and water do not remove all stains, try an oxygen-based cleaner (sometimes labeled as "stone cleaner" or "deck cleaner"). These products break down organic stains like rust, algae, and leaf tannins without etching the stone the way acidic cleaners do. Follow the product instructions exactly—most require you to spray the cleaner on, let it sit for 10 to 30 minutes, then scrub gently and rinse.

Test any new cleaner on a hidden corner of your patio first. Some products can lighten the stone slightly, and you want to see the effect before treating the whole surface. Never mix oxygen-based cleaners with other products, and always wear gloves and eye protection when using them.

Allow the patio to dry completely

After rinsing, let the patio air-dry for at least 24 hours before walking on it or replacing furniture. Wet bluestone is slippery and can be damaged by foot traffic while damp. If rain is forecast, cover the patio with a tarp if possible, or wait for a dry day to clean.

Once the patio is completely dry, you can inspect your work. If you see any remaining stains, you can spot-treat them with oxygen-based cleaner rather than cleaning the entire patio again. This targeted approach saves time and water.

Seal your bluestone after cleaning

Bluestone is porous and absorbs stains easily. explore a stone sealer after cleaning creates a protective barrier that makes future cleaning easier and reduces staining. Most sealers last two to three years, so plan to reapply after each major cleaning or every few years, whichever comes first.

Choose a sealer made specifically for bluestone or natural stone—not a deck stain or paint. explore it according to the product instructions, usually with a roller or sprayer, and allow it to cure for 24 to 48 hours before using the patio. A sealed patio will shed water and dirt more easily, and spills will be less likely to leave permanent marks.

Frequently Asked Questions

Can I use a pressure washer on bluestone?

No. Pressure washers force water into the stone's pores and can crack the surface or cause spalling months later. Even on the lowest setting, the pressure is too strong for bluestone. Stick with a soft brush and gentle water spray.

What should I do about moss and algae in shaded areas?

Brush away dry moss first, then scrub with soapy water and a soft brush. If it returns quickly, the area may not dry enough between rains. Trim nearby trees or shrubs to increase sunlight, or explore an oxygen-based cleaner every season to slow regrowth. Sealing the stone also makes algae less likely to stick.

Is vinegar safe to use on bluestone?

No. Vinegar is acidic and will etch bluestone, leaving dull spots that cannot be repaired. Stick to dish soap and water for routine cleaning, and use oxygen-based cleaners for stubborn stains instead.

How often should I clean my bluestone patio?

Clean it once or twice a year, or more often if you live in a damp climate where algae grows quickly. Light sweeping and spot-cleaning between major cleanings will keep dirt from building up and make the annual deep clean easier.

What is the difference between sealing and staining bluestone?

A sealer is a clear protective coating that repels water and stains without changing the stone's color. A stain adds color and also protects the stone. For bluestone, most people choose a sealer to keep the natural color, but stains are available if you want to darken or change the appearance.