Sumo Gardener

How to Create and Clean a Flagstone Patio Effectively

With flagstone flooring being so widespread in households across the globe, it’s essential to know how to properly go about your flagstone cleaning routine to keep your outdoor spaces looking their best. 

Luckily, it doesn’t take too much time or effort to keep flagstone looking pristine. As with any home care regime, proper maintenance is key to keeping our investments in top shape so that we can get the most out of their longevity and aesthetic influence. 

In this article, I will be detailing how you can go about your flagstone cleaning at home to keep your outdoor floors looking brand new for you, your family and your guests.


What are Flagstones?

How to Clean Flagstone

One of the most common types of garden stones used in the construction of pavements, walkways, driveways and patios is flagstone. It is most commonly used outside thanks to its durable and variable nature. 

A lot of garden owners opt for flagstone for their patios since they have narrow joints where the water can permeate freely. They also add an organic and natural aesthetic to outdoor spaces because of their shape and the earthy tones of blues, grays, reds, and browns they provide.

Some of the most common flagstone types used in the garden are limestone, slate and sandstone. It is also great for the backyard because of the durability that it has and the slip-resistant qualities that it provides, especially when the rains come.

How to Create a Flagstone Patio

Creating a flagstone patio is a relatively easy do-it-yourself project that can usually be tackled and completed in a weekend. While some patios call for tricky, involved concrete pours, this patio uses only water and sand to create.

There is very little maintenance for flagstones, as they do not shift or crack and damaged stones are easily replaced.

Here is how to create the perfect patio:

Clear and Outline the Area

You’re going to rake out the desired patio site, so try to pick a mainly level, smooth area and rake until the soil is evenly distributed. Get rid of any grass or other debris so you can lay the patio on dirt alone — there shouldn’t be any plants or weeds because they tend to peek through the stones.

Outline the desired shape of the patio with spray paint to define your area. You can also mark the outline string or rubber tubing. Since flagstones come in all different shapes and sizes, a site with curved edges is a better place to lay a patio than one with straight lines.

Rake and Excavate the Site

You’re going to dig out 2 or 3 inches of soil from the patio site by using a level and then using a piece of wood (2 x 4) to smooth out the surface. This will ensure your patio will be even with the rest of your yard once it is finished.

Putting the flagstones down 2 or 3 inches lets it be even with your yard once it’s put in, so be sure to grade the site as evenly as you can.

Put in a Base Layer of Sand

The flagstones will sit atop sand, so you’re going to pour sand into the excavated hole, about an inch from the highest edge. Rake this area until it is smoothed out using the 2 x 4 once again.

It’s recommended that you use “washed sand” for the patio, as it won’t retain as much water — it’s available for purchase at most soil yards.Then water the sand with a garden hose until it is moistened and pack the sand using a wooden board or hand tamper if you have one.

Position the Flagstones

Place the flagstones on your patio site, beginning at the outer edges and working your way towards the middle. You can pick the color of flagstone you want to use, as it comes in brown, tan, blue and red.

Position the bigger pieces first, and then fill in the spaces with the smaller flagstone pieces. Double check with the level of your yard when placing the stones to make sure it is even.

You should position the stones one to two inches apart on every side, making sure you keep the gaps consistent throughout the patio. As you place a stone, manipulate it to ensure the sand totally covers the bottom of the stone on every side.

Fill in the Cracks

You can pulverize bigger pieces of flagstone to fill in any leftover gaps by crushing it with a mallet or chisel. Place the pieces in a bucket and pour the crushed flagstones into any gaps you wish to fill.

Experts also recommend using decomposed granite, which is crushed rock and can be purchased in a tan shade, as a gap filler. Decomposed granite locks the flagstone pieces together, which in turn creates a solidified patio area.

When you pour, make sure to force the decomposed granite into each gap, eliminating any air gaps. Afterwards, sweep the excess decomposed granite into any remaining gaps.

Hose Down the Patio and Fill Again

Using a hose, gently water down the whole patio. This will make the decaying granite sink in and stay firmly in place. Repeat these two steps until the decayed granite is even with the flagstone.

And now you have a beautiful flagstone patio that is easy to maintain and looks great.

How to Clean Flagstones Effectively

No matter what your flagstones are being used for, it is always essential to know how to clean them to maintain their look, quality and longevity.

If you know how to properly clean flagstones, they will naturally last for an extended period, giving you more bang for your buck at the end of the day. 

Whether you choose to use a specified flagstone cleaner and flagstone sealer or you want to go about it using general household items, knowing what to look for and how to perform the cleaning correctly is vital to maintaining a good-looking yard.

Removing Excess Water from Flagstones

The first thing that you need to do is to brush away any water and condensation that is present on the flagstone with the help of a squeegee or outdoor sweeper.

It is important to make sure that your flagstone is free from any moisture to prevent the build-up of mineral deposits which can lead to the advanced withering of the stone.

Sweeping Off Dirt from Flagstones

Once dry and free from moisture, it is also recommended to regularly sweep your flagstone using a dust mop or a dry broom to remove the debris, dirt and dust.

You can do the sweeping during the time that you are doing your cleaning tasks, typically after a windy day or after a gathering. Removing debris regularly will avoid your flagstone from developing any permanent stains and discolorations. 

A man using a pressure washer on flagsone

Removing Flagstone Stains

Now, if there are already stains including mildew and mold stains, then using outdoor bleach will help. Prepare a solution of diluted bleach then start spraying the area where the stains are and scrub them gently using a tough deck brush.

After treating it, you need to rinse it off with water immediately. If the bleach accidentally gets into contact with your plants or your grass then immediately wash it off with water to avoid damaging them. Reapply as needed.

Alternatively, you can use white vinegar to remove tough stains. Pour some white vinegar over your flagstones, allowing it to sit for a couple of minutes.

Then, using a tough sponge or sweeper, scrub the vinegar into the stone, focusing on the stains as much as possible. Give your floor a good rinse afterwards and reapply as needed to reduce the staining.

Using a Flagstone Cleaner

There are specialized flagstone cleaning products available with a neutral PH level and other important ingredients that are formulated to keep your flagstone looking impressive all year round.

Simply mix the solution as instructed with some hot or warm water then, with the help of a mop, low-pressure sprayer and sponge, you can apply and scrub the solution into the flooring.

Garden Flagstone Maintenance

Garden Flagstone Maintenance

Maintaining your flagstones is important for you to do in order to ensure they last and look their best for as long as possible.

Sure, eventually they may need to be replaced but you can ensure the ultimate longevity of your flagstone structures by regularly cleaning and looking after them.  

Regularly Check for Damages

One of the first things that you need to do is to regularly check your flagstone to see if there are any damages present. By noticing damages as soon as possible, you can get to fixing them before the damage gets worse. 

One of the biggest benefits of having flagstone is that whenever one tile becomes damaged, you don't need to replace the entire floor. Since they are installed one by one, you can simply just replace the tiles that are damaged with new stones. 

Using a Flagstone Sealer – How to Seal Flagstone

Another vital step to maintaining flagstone is to apply a specialized flagstone sealer that fills the pores of your flagstones and repels spills.

Apply a flagstone sealer on all stones but especially on the ones where the water supply coming into contact with the stones contains heavy minerals or alkaline.  

Typically, flagstone sealer products should be applied right after the installation of the tiles, once they are clean and dry.

Many homeowners recommend avoiding sealers that have a glossy finish to them as this can affect the natural beauty of your flagstone and take away from that organic look and feel. 

Some sealers have a matte finish, which is an ideal alternative since it will help maintain the appearance of the flagstone.

You can simply apply the sealer using a brush or a roller as instructed on the packaging of the product. You can also choose to occasionally reapply the sealer to ensure that your flagstones will stay as protected as possible.

Flagstone Cleaning Guide

Caring for Your Flagstones in the Winter

Now, once the winter season settles in, it would be best to remove any snow that has been laying on the flagstone as soon as possible before it melts or freezes over. 

The reason behind this is that it will help to avoid overly moist conditions in the stones and keep the ice from going inside the joints and damaging the flagstone from within. 

If too much moisture gets into the pores of the stone and freezes, it could lead to unwanted cracks and gaps once they heat up again and fracture.

Flagstone Cleaner and Sealer Recommendations 

Flagstone Cleaners

1. Wet & Forget Outdoor Multi-Surface Cleaner

Wet & Forget Outdoor Multi-Surface Cleaner

This convenient, ready-to-use stain remover solution offers fantastic results with little effort. You just need to apply it to the stone surfaces and that’s it, the product will do the rest for you. No rinsing, scrubbing or power washing is required. 

2. Black Diamond Stoneworks Limestone and Travertine Floor Cleaner

Black Diamond Stoneworks Limestone and Travertine Floor Cleaner

Formulated to protect stone surfaces and enhance their natural beauty by making colors more vivid with frequent use, this flagstone cleaner offers great value for money while being a quality product.

It is made from natural ingredients so it's safe for use around children, pets and the environment. 

3. Simple Green Oxy Solve Concrete and Driveway Pressure Washer Concentrate

Simple Green Oxy Solve Concrete and Driveway Pressure Washer Concentrate

This environmentally friendly pressure washer concentrate is perfect for eliminating tough stains and grime from your patio, walkways or driveway.

It is designed to complement your pressure washer to offer a more detailed cleaning experience outdoors. 

Flagstone Sealers

1. Foundation Armor WL550 Matte Look Enhancer Sealer

Foundation Armor WL550 Matte Look Enhancer Sealer

This is a fantastic all-around sealer that is perfect for flagstone. It penetrates deeply where the solution forms a hydrophobic barrier within the pores of the stone to reduce surface water absorption by up to an impressive 95%.

It will also help to enhance the stone's color by darkening it slightly with a clear matte coat.

2. Serveon Sealants H2Seal All Purpose Stone Sealer

Serveon Sealants H2Seal All Purpose Stone Sealer

Assisting with prolonging stone life while retaining that natural look, this premium stone sealer is easy to apply and is made from quality ingredients.

It utilizes an advanced siliconate sealer repellent technology to offer ultimate water protection and decreased moisture abortion. 

3. Dominator Matte Acrylic Stone Sealer

Dominator Matte Acrylic Stone Sealer

Another premium sealant, this acrylic-based sealer offers fantastic value for money with its impressive coverage rate and its luxurious matte finish.

It is a professional-grade sealer that will enhance the life and beauty of your stone surfaces. Available in a convenient 1 Gallon container. 

Frequently Asked Questions About How to Clean Flagstone Patio

How do you remove stains from flagstone?

An effective way to remove stains and grime from flagstones is to use a diluted bleach solution on your flagstones. Usually, a combination of one-part bleach and ten parts water is recommended.

Use a tough sponge and gently scrub the solution across the surface of the stones then rinse well with water. Multiple applications may be necessary depending on how dirty the flagstones are. 

How to restore the color of flagstone?

Staining flagstone is a great way to help restore some color and vibrance to your stones. Rinse the surface of your flagstones and allow them to dry. Then, fill a container with a mixture of water and a mild concrete stain solution.

Pop the mixture into a sprayer then apply a solid layer to your stones one at a time, using a broom to work the stain solution into the stones.

Is it okay to pressure wash flagstone?

Yes, you can use a pressure washer on flagstone but you just need to be sure you do it properly to avoid damaging the stones. It is best to use a low pressure to avoid harsh contact and make sure you or the contractor is using hot water. 

How do you remove black stains from flagstone?

Vinegar is an excellent cleaning product to use to remove black stains from flagstone. Pour some white vinegar over your flagstones, allowing it to sit for a couple of minutes.

Then, using a tough sponge or sweeper, scrub the vinegar into the stone, focusing on the stains as much as possible. Give your floor a good rinse afterwards and reapply as needed to reduce the staining.

How do you make flagstone shine?

You can polish your flagstone to make it shine. Mix some warm water with a couple of drops of liquid dish soap and clean the flagstone by scrubbing it. Rinse and let it dry.

Then, spray the flagstone with a natural stone polish, using as little as possible. Gently rub the polish into the stones using a clean cloth and circular motions.

Buff the polish with another clean cloth until the surface is shiny and dry. 

Why does flagstone turn white?

This happens when water-soluble salts move onto the surface of the stones with the help of water from rain or condensation. Once this water hits the stone surface, it mixes with carbon dioxide in the air and creates a white film that covers the surface. This occurrence is known as efflorescence. 

Should you seal flagstone?

All flagstone surfaces are prone to water stains outdoors. Water contains harmful mineral deposits and alkaline that will damage flagstones over time.

Because of this, all new flagstone paving must be sealed upon completion to protect it from water damage. 

Why does flagstone crack?

This is caused by repeated freezing and thawing of moisture in the stones. This is why you should avoid letting water or snow sit on the flagstones for too long by sweeping it away as soon as possible.

Take Your Flagstone Cleaning to the Next Level

I hope you have a better understanding of how to go about your flagstone cleaning to ensure you have beautiful outdoor spaces for years to come. 

Regardless of which flagstone cleaner and flagstone sealer you choose, your paving will certainly thank you for the extra TLC by retaining a tip-top appearance for you to enjoy. 

Take your flagstone cleaning to the next level by following our simple steps above.

About the Author Pat Moreno

Pat is our gardening tool expert here at Sumo Gardener. Working for many years as a private and commercial landscaper, Pat has used almost every type of gardening tool there is. Along with a vast knowledge for types of plants and putting together an amazing looking and maintainable garden, Pat developed a passion for gardening tools as he found that using the right tools vastly improved the ease and outcome of any landscaping job he undertook. When spending hours, days or years using a particular tool, you want to make sure you’ve got the best one for the job, and Pat is the right guy to guide us to the best gardening tools.

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