Dirt can accumulate on flagstone over time which can result in stains and mildew. To prevent this problem, regular maintenance should be done to keep its color and appearance.

Time estimate for general cleaning: 30-45 minutes, depending on the size of the area
Time estimate for stain removal: 10-20 minutes, depending on the amount and type of stain

This Skill provides step-by-step instruction on how to:

1. Prepare the solution
2. Apply the cleaning mixture
3. Scrub and rinse the stone
4. Remove deep stains and weeds
5. Thorough cleaning of flagstone patio
6. Remove biological stains (algae, mildew, lichens, moss, fungi)
7. Maintain flagstone without grout

For general flagstone cleaning, you will need:

1. Flagstone cleaner solution (depending on the type of stone)
2. Water
3. Bucket
4. Stiff push broom or brush. Note: Do NOT use a broom or a brush with wire bristles
5. Hard bristle brush
6. Garden or washer hose
7. White vinegar
8. Spray bottle

For thorough cleaning, you will also need:

1. Muriatic acid

For removing biological stains, you will also need:

1. Hydrogen peroxide, household ammonia or bleach

For flagstone without grout, you will also need:

1. Polymeric sand