Home Improvement
Outdoors
Clean your concrete patio of tough stains
By
Mary Marlowe Leverette
Mary Marlowe Leverette
Mary Marlowe Leverette is one of the industry's most highly-regarded housekeeping and fabric care experts, sharing her knowledge on efficient housekeeping, laundry, and textile conservation. She is also a Master Gardener with over 40+ years of experience and 20+ years of writing experience. Mary is also a member of The Spruce Gardening and Plant Care Review Board.
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Updated on 04/17/24
Reviewed by
Becky Rapinchuk
Reviewed byBecky Rapinchuk
Becky Rapinchuk is a natural cleaning expert, home-keeping expert, and founder of the lifestyle brand, Clean Mama. She has published 4 best-selling books on cleaning.
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In This Article
Before You Begin
Unsealed Concrete
Mildew Stains
Grease Stains
Prevention
Concrete patios and driveways are practical, affordable, and durable. With design innovations like adding color stains, stamping, and sealers, concrete is no longer just a hard, dull gray surface and has even moved inside the home as an interior floor or countertop. Even though outdoor concrete is exposed to harsh weather and lots of use, with just a bit of care, concrete patios can look beautiful for decades.
How Often to Clean Concrete Patios
Most patios only need to be cleaned once per year. Spring is a good time to clear away winter mud and grime. However, if you have food stains or drips of grease from a barbecue grill, you may want to add a thorough cleaning in the fall.
Before You Begin
When cleaning a concrete patio, make sure you choose a mild, overcast day to tackle the job, so that the cleaning solution will not evaporate too quickly. You'll want to clear the space, removing all furniture, grills, plants, and toys from the patio. Use a broom or leaf blower to eliminate all loose debris. Then, use a garden hose with a spray nozzle to wet down the concrete.
What You'll Need
Equipment / Tools
Unsealed Concrete Patios
- Broom or leaf blower
- Garden hose
- Sponge mop
- Nylon-bristled scrub brush
Red Mud & Rust Stains
- Nylon-bristled scrub brush
- Garden hose or power washer
Mildew Stains
- Spray bottle or sponge mop
- Old towels or plastic sheeting
- Eye protective gear
- Nylon-bristled scrub brush
- Garden hose or power washer
Grease Stains
- Broom
- Nylon-bristled scrub brush
- Garden hose
Materials
Unsealed Concrete Patios
- Distilled white vinegar
- Baking soda
Red Mud & Rust Stains
- Oxalic acid or a commercial cleaner containing oxalic acid
Mildew Stains
- Chlorine bleach
- Water
Grease Stains
- Kitty litter or cornstarch
- Commercial degreaser
Instructions
How to Clean Unsealed Concrete Patios
Just a few supplies and a bit of elbow grease are needed to clean a patio. If the concrete is heavily stained, you may wish to use a power washer and a commercial cleaner recommended for the washer. Do not use a vinegar and baking soda mixture in a power washer.
Mix the Cleaners
Pour one cup baking soda into a plastic bucket or bowl. Slowly add two cups of distilled white vinegar. The mixture will foam up but will settle if you mix it slowly. The consistency should be like a cream soup—thick enough to cling to the surface but not too thick to spread. Spread the mixture over the concrete with a sponge mop. Depending on the size of the patio, you will probably need to double or triple the ingredients.
Scrub, Scrub, Scrub
Allow the mixture to sit on the concrete surface for around 30 minutes. Use a nylon-bristled scrub brush (metal brushes can leave small pieces of metal in the concrete that will rust) to clean the entire surface. Use a scrub brush with a long attachable handle to save your back and knees.
Rinse and Dry
Rinse away the cleaning solution. Make sure to spray clean water on any shrubbery or grass next to the patio that may be splattered with the vinegar and baking soda. Allow the concrete to air dry completely before replacing any furniture and accessories to prevent staining.
How to Remove Red Mud and Rust Stains
Rust stains from furniture legs and grills can be especially difficult to remove. In some areas of the country, the soil contains so much iron that red mud stains must be treated like rust stains. Rust stains should be treated before removing mildew stains. Chlorine bleach can permanently set in rust stains.
Apply the Cleaner and Scrub
Sweep away any debris from the stained area. Follow the directions on the packaging of oxalic acid-based cleaner and apply it to the stained area. Scrub with a nylon-bristled brush.
Rinse and Dry
Rinse away cleaner with clean water and allow the area to dry. Repeat if stain remains.
How to Remove Mildew Stains From Concrete Patios
Quite often, heavy mildew stains will appear on concrete due to outdoor dampness. To effectively kill the mildew spores and remove the black stains, you will need to use chlorine bleach. Oxygen-based bleach will remove the stains but will not kill the spores.
Clear the Patio and Mix the Cleaner
Mix a solution of one part chlorine bleach to two parts water in a plastic bucket or spray bottle after you have removed everything from the patio. You will need to protect the lawn and shrubbery from the solution with old towels or plastic sheeting. The bleach will burn and possibly kill greenery. Always wear old clothes to prevent bleach spotting and protective eyewear for safety.
Apply and Wait
Spray on the bleach solution or use the mop to spread the solution onto the mildew-stained areas. Allow the cleaner to work for five to 30 minutes depending on how heavy the stains are on the surface.
Scrub and Rinse
Scrub the concrete with a nylon-bristled brush and then rinse thoroughly with the garden hose. For extremely heavy stains, a power washer provides a much stronger stream of water to blast away the grime. Use a hose to rinse greenery after the patio is clean.
How to Remove Grease Stains
Grease stains should be treated as soon as possible after they happen because concrete is porous and the longer the grease sits, the deeper it goes into the surface. Be patient; you may need to treat grease stains several times before they disappear.
Apply the Cleaner and Wait
Sprinkle the grease stain with a thick (at least one-inch) layer of kitty litter or cornstarch. Allow it to remain on the stain for 24 hours or up to three days to absorb the grease.
Check, Scrub, and Rinse
Sweep up the kitty litter and inspect the stained area. If it remains, repeat step one. If the stain is nearly gone, spray the area with a commercial degreaser and scrub the stain with a nylon-bristled brush. Rinse with a garden hose and allow to dry. Repeat if needed.
Tips to Prevent Stains on a Concrete Patio
While it is possible to clean stains off a concrete patio, the best thing you can do is to prevent them from occurring in the first place. There are a few things you can do to protect your concrete patio against stains:
- Apply a concrete sealer to the patio every two to three years to keep it protected.
- Perform an annual cleaning to remove the surface dirt. This includes rinsing and/or power washing.
- Keep your patio clear of sitting debris such as leaves and branches.
- Sweep and blow your patio regularly to prevent dirt and dust from accumulating.
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