How to Clean Flagstone: The Ultimate Step-by-Step Guide

Margaret Jul 01, 2026

Flagstone is a durable, natural material often used for patios, walkways, and retaining walls. Over time, however, it can accumulate dirt, mold, and mildew, detracting from its aesthetic appeal. Regular cleaning is essential to maintain the beauty and longevity of your flagstone surfaces. Here's a comprehensive guide on how to clean flagstone effectively and safely.

How to Clean Flagstone Patios | Homesteady
How to Clean Flagstone Patios | Homesteady

Before you begin, ensure you have the right tools and materials. You'll need a stiff-bristled brush, a broom, a garden hose with a spray nozzle, a bucket, mild dish soap, a scrub brush, and, if necessary, a pressure washer and a suitable cleaner for tough stains or moss.

Best Way To Clean And Seal Flagstone To Remove And Prevent Mold And Algae
Best Way To Clean And Seal Flagstone To Remove And Prevent Mold And Algae

Preparing the Surface

Start by removing any debris from the surface using a broom. This will make the cleaning process more efficient and prevent damage to your tools.

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How to Clean Flagstone Floors with Milk

Next, wet the surface with clean water to soften any dirt or stains. This will make it easier to remove them during the cleaning process.

Choosing the Right Cleaning Method

how-to clean dry laid flagstone | how-to install stone dust in the joints
how-to clean dry laid flagstone | how-to install stone dust in the joints

For light dirt and stains, a simple solution of mild dish soap and warm water is usually sufficient.

Soap and Water Cleaning

Mix a few drops of mild dish soap with warm water in a bucket. Dip your stiff-bristled brush into the solution and scrub the flagstone in small sections. Work from the top of the surface downwards to avoid spreading dirt around.

How do I Clean Outside Stone Paving?
How do I Clean Outside Stone Paving?

Rinse each section thoroughly with clean water using your garden hose to remove all soap residue. Allow the surface to dry completely before using it again.

Pressure Washing

For tougher stains or moss growth, you may need to use a pressure washer. Ensure your washer is set to a low pressure setting to avoid damaging the flagstone.

an old cobblestone street with no cars on it
an old cobblestone street with no cars on it

Use a suitable cleaner for tough stains or moss, following the manufacturer's instructions. Apply the cleaner to the surface, let it sit for the recommended time, then use the pressure washer to rinse it off thoroughly.

Sealing the Surface

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5.7K views · 9.2K reactions | Watch until the end ➡️ • When it comes to flagstone, we like to keep it clean with consistent joint spacing. How big? Think #2FingerJoints ✌️ • Want to master the technique? Our full flagstone installation tutorials are available on-demand. Get signed up today! 🎥 • #Hardscapetraining #hardscape #hardscaping #flagstone #hardscapedesign #patio #pavers #outdoorliving #construction #build #hardscapementor #outdoorpatio #patiodesign #patiolife #diy #contractor #contractorlife #bluecollar #landscaping #landscape #yard #backyard #outdoorlivingspace | Hardscape Mentor | Facebook
5.7K views · 9.2K reactions | Watch until the end ➡️ • When it comes to flagstone, we like to keep it clean with consistent joint spacing. How big? Think #2FingerJoints ✌️ • Want to master the technique? Our full flagstone installation tutorials are available on-demand. Get signed up today! 🎥 • #Hardscapetraining #hardscape #hardscaping #flagstone #hardscapedesign #patio #pavers #outdoorliving #construction #build #hardscapementor #outdoorpatio #patiodesign #patiolife #diy #contractor #contractorlife #bluecollar #landscaping #landscape #yard #backyard #outdoorlivingspace | Hardscape Mentor | Facebook

After cleaning and allowing the surface to dry completely, consider sealing it to protect it from future dirt and stains. Use a suitable sealant designed for flagstone, following the manufacturer's instructions.

Sealing will not only protect your flagstone but also enhance its natural beauty, making it easier to clean in the future.

Regular cleaning and maintenance will ensure your flagstone surfaces remain a beautiful and functional part of your outdoor space. Don't wait until they're dirty to clean them; incorporate it into your regular home maintenance routine for the best results.