How to Remove Walnut Stains from Concrete

Walnuts may be a delicious treat on salads but they can be a nuisance on driveways and patios, especially those made of concrete. While forging the delicious treats can be an exciting activity for families, walnuts can actually leave unwanted stains on concrete surfaces and human skin.

Black walnuts in particular can leave hard-to-get-rid-of stains on skin and even cause irritation and burning if left on long enough.

The key to keeping hands and other exposed flesh from staining is to wear gloves. This will prevent any irritation or unsightly discoloration while collecting or removing walnuts from the area in question.

Before heading out to cut down that walnut tree, consider trying to remove the walnut stains altogether. There is one proven method that has been recommended time and time again, so don’t be discouraged.

Removing walnut stains on concrete close up

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Removing Walnut Stains From Concrete

If walnut trees plague a homeowner’s driveway, patio, or concrete area the only solution for stain removal is granular chlorine which is a heavy-duty cleaner.

Granular chlorine is the same chemical used in swimming pools and is highly corrosive and extremely harmful. This means caution will need to be taken when using and cleaning the afflicted area.

The materials needed to remove walnut stains include protective gloves, protective eyewear, rubber boots, a garden hose, granulated chlorine, a spray bottle, a mop bucket, a bristle brush, Dawn dish detergent, and borax. Once all those items have been collected is when the work begins.

Start by gearing up with disposable or rubber gloves or protective eyewear for safety.

To begin advises to dampen the stained area with the garden hose and be sure to cover the entire stain. Avoid over-watering. If puddles develop, wipe them away or wait for them to dry.

Next, apply the chlorine granules to the stained area using a spray bottle to mist the granules. Once the chlorine is sprayed, it should immediately start working to clean away those unsightly stains. Wait five minutes before touching the area.

In the meantime, fill the mop bucket with a gallon of hot water and add four tablespoons or 1/3 cup of Dawn dish detergent and 2/3 cup of borax. Mix these together thoroughly until combined.  Once the five minutes have passed, scrub the area vigorously.

The longer the area is scrubbed, the more successful this will be. Once satisfied with the work, rinse the area by clearing away all soap or chemicals.

Make sure to examine the area once complete. The stain should be gone. If it is not, let the area dry before attempting to remove it once again. Repeat this process until the desired result is achieved. suggests applying a coat of concrete sealer to the newly stain-free area. Applying the sealer will make handling future stains easier to clean or even prevent entirely.

Rather than remove the stains themselves, some homeowners opt to cut down the pesky walnut tree to avoid any future problems. This is also an option, although it may come at a price.

It’s recommended that calling a professional tree cutting service is best when removing unwanted trees to avoid any personal injury or damage to nearby structures.

Black Walnuts And Staining

Black walnuts may be tasty treats, they also contain a toxin that is deadly to plants and cause irritation in humans. The shell itself is non-toxic, but inside where the walnut resides, under the husk is where problems can occur.

According to, black walnuts produce a toxic chemical referred to as juglone. This chemical is responsible for damaging vegetation and causing skin reactions in humans.

Dermatologist, Dr. John Anthony says, “It causes the production of a chemical that binds to the skin and has this dark colouring, almost black.” He goes on to note that coming in contact with black walnuts or the chemical juglone can cause pain, itching and severe blistering.

While there is no association to a nut allergy, Dr. Anthony says, “Because it’s an irritant, you won’t have the kind of allergic reaction you get from a bee sting. The real danger is the skin on your hands getting torn up from the blisters. It not only makes it hard for you to do many daily tasks but you also risk infection.”

The easiest way to avoid coming in contact with juglone is to wear gloves when handling black walnuts. Disposable gloves are best since they are easy to get rid of which means there’s less of a risk in spreading the juglone on anything else. Rubber gloves work as well, but it’s important to thoroughly wash them after use with soapy water to ensure they are clean.

Staining from a black walnut is similar to the staining of henna, Dr. Anthony says. Depending on how long they are handled, hands or other parts of the skin may turn black where the walnut has been. The same goes for outdoor areas like patios.

In referencing the skin, Dr. Anthony says, “This pigmentation is semi-permanent. It just has to wear off and it can take a long time to fade.”

Be wary of the skin where the walnut has touched as blistering can occur. These blisters can be painful, but it is advised that they be left alone and untouched. If large, painful blisters arise medical treatment may be necessary to avoid infections.


Walnuts are capable of staining concrete due to a chemical found in the hull of the shell known as juglone. While this chemical is deadly to vegetation, it merely causes some minor irritation in humans.

Coming in contact with the chemical can cause the skin to turn black in pigmentation, similar to henna, which can be difficult to remove. On concrete or other surfaces it can also cause problems in the removal process.

Wearing protective gloves when collecting cracked or whole walnuts is key to preventing any painful or potentially harmful side effects of black walnuts. Burning, itching or blistering may occur on the skin. If blisters become large and painful seeking medical treatment is advised to avoid any potential risk of infection.

It’s important to have all the necessary equipment when addressing the stained concrete area, especially protective gloves. These will prevent any discomfort that one may experience when handling black walnuts or the chlorine cleaning agent.

Granular chlorine is the only cleaning agent successful enough to remove walnut stains from concrete. Following the step-by-step instructions should result in complete removal. If the stains are not removed to one’s satisfaction, the process may need to be repeated until the desired result is achieved.

While some choose to clean away minor stains here and there every once in a while, for others the problem can be eradicated completely by simply removing the tree. Using a professional tree service is recommended.