Does human urine kill grass? Maybe you hurriedly relieved yourself on your lawn one day and realized that the patch had turned yellow or brown the next day.

Comprehensive Analysis of Human Urine on Grass

This is not surprising because human urine in its concentrated form can be quite toxic and potentially burn grass and weeds.

We have compiled this article to discuss how human urine can be useful and dangerous to lawn grass. 

Does Human Urine Kill Grass?

Yes, human urine can kill grass and damage the lawn if it is applied undiluted and repeatedly. At least three applications of human urine on a single spot are enough to burn the grass blades down to their roots. Using certain medications regularly makes urine especially toxic for grass.

– Ways of the Affects 

How urine affects grass depends on the composition of urine, the condition of the grass, and the soil on which it falls. Healthy human urine has high water, low sodium levels, and nitrogen from ammonia and urea.

Note that healthy urine is already well-diluted by the kidney, but you must dilute it further before applying it to the grass. Used this way and sparingly, urine can be a potent soil nitrogen source. 

However, most people don’t drink enough water to produce healthy urine and then urinate on the grass without dilution.

Human Urine on Grass

Note that the high ammonia levels in urine will turn grass blades yellow from chemical burns because this waste is very low in its pH.

On the other hand, if urine comes from a person on certain medications, high sodium diet, or is dehydrated and very much waste-concentrated, it makes urine even more dangerous for the soil and anything growing.

Note that the human urine also contains a significant amount of uric acid and might even lower the pH of the soil. Grassroots prefer the soil pH to be neutral to alkaline and suffer when the soil becomes slightly acidic.

– Cleaning The Toxicity

Say some ignorant guest decides to relieve themselves on your precious lawn grass. What can you do immediately before their pee kills off an entire patch of grass? Wash off the urine from the grass using a copious volume of water. 

The sooner you wash pee off, the lesser the damage will be. Next, apply baking soda because it is a known antidote or the remedy to concentrated urine. 

Cleaning Grass to Reduce Toxicity

Some grass blades that come in contact with the urine will get burnt so quickly due to the abundance of acid, but water and irrigation can prevent it from seeping deeper toward the roots.

However, if some time passes before you know of it, then it might be possible that the urine has had time to kill some grass and alter the soil’s pH. 

Still, you may have to irrigate the area deeply, apply baking soda and then wait a few days. Take out the old grass that has died and carry out soil testing.

If the pH has been affected, add soil additives, such as lime, to correct it. Lastly, remember to replant the grass in the bare spot and fertilize it to speed up its growth.


Does Dilute Urine Kill Grass?

No, dilute urine does not kill grass, on the contrary, it is a way to fertilize grass, it can treat the fungal infestations in the soil. In addition, it may also improve the quality of the soil and kill the weed that grow, and it keeps the unwanted animals away.

– Fertilize Grass

You can utilize human urine’s potential as a rich source of nitrogen, phosphorus, potassium, and other important nutrients and use it as a fertilizer for grass. Consider it; diluted human urine makes for a very eco-friendly grass food.

You must always dilute urine in a ratio of approximately 20 parts water to one part urine. You can apply it evenly on the soil using a spray bottle or sprinkler. A sprinkler would be better because it wets the lawn uniformly and will reach spots you might miss during manual spraying and spread it all around. 

As you are using this fertilizer, every one to two weeks should be enough to be enriched.

A more frequent application would deliver an excess of nitrogen, and the grass will turn yellow instead of greenery. Take care that you collect urine samples from healthy people who drink lots of water and are preferably not on any medication.

– Treating Fungal Infections

Human urine contains a significant quantity of uric acid, which has several benefits in lawn care. Uric acid effectively treats fungal diseases such as powdery mildew, root rot, etc.

To use urine as a fungicide, dilute it using 20 or 10 parts water with one part urine. Place this mixture in a spray bottle and spray on the grass patches that seem visibly affected. In mildew, the fake grass will be covered in white spots, while rotten grass will have brown spots and stink badly.

Fungal Infections on Grass

The more you dilute the urine, the antifungal effect will be less potent. You will need frequent re-applications to eradicate the infection. Try spraying the diseased grass once a week until the spots are all gone. 

These diseases might affect your grass when overwatered or contaminated by unclean instruments. Using chemical fungicides means exposing the grass and the soil to chemicals that tend to be quite harsh. This is when you can use diluted humans instead as a natural and safer alternative.

– Diluted Urine Can Improve Soil

Over time your lawn gets depleted of essential nutrients like potassium and phosphorus. Diluted urine is still a pretty rich source of these important nutrients. Autumn is the most optimal time to add some urine to your soil when the grass begins to undergo winter dormancy. 

The dead roots and leaves in the soil decompose faster when you pour urine over them. In this way, you can help create compost in the soil naturally. After spreading mulch or compost over the soil surface, pour a small amount of diluted urine over them to accelerate their breakdown. 

– Can Kill Weeds

Without dilution, urine is too toxic to let grass and weed live and can be utilized as a potent weed killer.

Human urine kills all plantations due to urea, ammonia, uric acid, and other harmful toxins being eliminated from the body. If you have weeds growing in patches over the lawn or grass sprouting between driveway stones, pour a little pee over these areas. 

The most concentrated and toxic urine is obtained early in the morning after a full night’s sleep. Collect significant pee from all household members in a plastic spray bottle with a nozzle. It is not required for it to be diluted it in this case.

Wait for the morning dew on the grass and weed patches to dry first. If it has rained anytime in the past 24 hours, you must wait until your target areas are bone dry.

Water and dew drops will dilute the urine and decrease its potency as a weed killer. Spray a generous amount, and the targeted weeds turn yellow and brown. 

In this case, you may have to hold the dead grass and weeds by hand and pull them up from the roots.

Dead weeds are very easily pulled out compared to one that is alive. Don’t expect the weeds to die completely after a single application. You will need to keep applying urine every other day until all the weeds are gone.

Try to use urine sparingly and for too long, though. You might end up adding excessive nitrogen to the soil, along with altering its chemistry. This would make it difficult for healthy grass and plants to grow in the vicinity. 

– Keep Animals Away

Urine naturally smells bad. It smells a hundred times worse than our animal friends with a keen sense of smell, such as dogs, cats, and rodents. In this case, you want to keep certain animals out of your lawn for many reasons and with the smell of the acidic liquid, they will be away.

At the same time, it is important to keep your pets away from the grass when fertilizing it. This is especially necessary when using stay-on-the-surface natural fertilizers such as compost or manure.

Spray a little bit of diluted urine along the periphery of your lawn to keep your pets at bay. Your pets will stay away from it, and this is because the fertilizer may harm the animals and intoxicate them, so keeping away with diluted urine is the best option.

Keep Animals Away from Urinated Grass

In many neighborhoods, lawn owners are sick and tired of animals visiting their lawns at night in search of food.

These animals include rodents, moles, raccoons, skunks, etc., and they destroy grass and plants, for example if they have planted some vegetables near the grass, they would come at night and eat it, like wild rabbits for instance. 

When you observe and see which spots are most frequently visited by these unwanted guests that is when you can spray a generous amount of diluted urine there.

Around the lawn, it is better to use undiluted urine because its stronger smell will be more intolerable for these animals, yet again the undiluted one should not be on the grass, it can be on other surfaces that won’t burn. 


Human urine will kill the grass, but if you actually dilute it properly, it will give you more benefits than you imagined.

This article discovered how diluting human urine converts it from toxic to useful fertilizer:

  • Undiluted urine is too toxic, kills grass, and alters the soil’s biochemistry.
  • When diluted, human urine can be used as an effective feed rich in nitrogen, phosphorus, and potassium.
  • Diluted urine protects other animals from your lawn and treats fungal infections.

If you thought it was okay to let your kids or pets urinate freely around the lawn, then we hope this article has helped change your mind. You have also learned how to properly utilize the hidden potential of urine by diluting it with water in a ratio of one to 20.

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