Does Urine Kill Plants? – All You Need To Know About This Human Waste

Does Urine Kill Plants

Last Updated on July 23, 2023 By Emma W. Thomas

Yes, urine can kill plants if applied in large quantities or directly onto the plant. The high concentration of nitrogen and salts in urine can damage plant roots and lead to dehydration. Diluting urine with water or avoiding direct application to plants can minimize harmful effects.

5 Reasons Why an Excess of Urine in the Soil Can Kill Plants

Urine is a natural substance that can be used as a fertilizer due to its high nitrogen content. However, when used in excess or in concentrated amounts, it can have detrimental effects on plants. Let’s explore the reasons why too much urine in the soil can potentially harm and even kill your plants.

  1. High Nitrogen Concentration:
  • Urine contains a high level of nitrogen, which is an essential nutrient for plant growth. However, excessive nitrogen can disrupt the balance of nutrients in the soil, causing nutrient imbalances in plants.
  • The result is an unhealthy environment for plants as their root systems may not be able to access other vital nutrients like phosphorus, potassium, and micronutrients.
  • Plants overwhelmed by excessive nitrogen may experience nutrient deficiencies, stunted growth, and even death.
  1. Imbalanced pH Levels:
  • The pH level of soil plays a crucial role in the availability of nutrients to plants. The normal pH range for most plants is slightly acidic to neutral.
  • Although urine is slightly acidic when excreted, it quickly becomes alkaline as it decomposes. This alkaline effect can raise the pH levels of the soil, making it unsuitable for many plants.
  • When the soil pH becomes imbalanced, it can hinder the absorption of essential minerals, leading to nutrient deficiencies and poor plant growth.
  1. Salt Build-up:
  • Human urine contains salts, such as sodium, potassium, and chloride. These salts can accumulate in the soil over time.
  • The build-up of salts can increase the osmotic pressure in the soil, making it difficult for plants to absorb water through their root systems.
  • Increased salt concentration in the soil can cause dehydration in plants, leading to wilted leaves, brown patches, and, in severe cases, irreversible damage.
  1. Toxic Substances:
  • Apart from nutrients, urine can also contain various toxic substances, including medications, caffeine, and other chemicals from our diets.
  • Plant roots can absorb these substances, which can interfere with their natural physiological processes.
  • These toxic substances can disrupt plant metabolism, inhibit nutrient uptake, and eventually lead to plant death.
  1. Overwatering Effect:
  • Urine applied in large quantities can saturate the soil, causing overwatering.
  • Overwatered plants can suffer from root rot and suffocation, as oxygen cannot reach the roots.
  • Root rot can lead to the decay of the root system, rendering the plant unable to absorb water and nutrients effectively.

What Are Some Benefits Of Applying Urine To Your Garden?

Urine has various uses and benefits in the garden, including;

Use As A Fertilizer

Urine, just like commercial fertilizers, contains large amounts of nitrogen which is essential for plant growth. This nutrient helps the plant manufacture enzymes, amino acids, chlorophyll, and proteins necessary for all crops. You can use urine as a fertilizer in your garden but be sure to dilute it with enough water. 

You can mix water and pee in a ratio of 20:1 (20 volumes of water and 1 volume of urine). Place the mixture in a watering can and apply it to the soil around the plants. Make sure that you don’t use the liquid directly on your crops. 

For Soil Enhancement

Since urine is also rich in potassium and phosphorous besides nitrogen, it can replenish the soil. Over-cultivating your garden can deplete the essential minerals which need to be replaced. Applying generous amounts of diluted urine in your garden can do wonders as far as enhancing the soil is concerned. 

Accelerating Your Compost

The process of decomposing vegetable matter into fertilizer for use in your garden may take a lot of time. You can add urine onto your compost to accelerate this process since it contains uric acid that helps break down materials constituting the compost. Make sure that you add enough undiluted urine to your compost.

For The Elimination Of Weeds

As mentioned earlier, urine consists of uric acid that kills plants if it comes into contact with them. This acid will not only be harmful to important crops but also to weeds. You can apply this solution (undiluted) to any undesirable weeds in your garden to get rid of them.

It Balances The Amount Of Carbon In The Soil.

The soil consists of broken-down, dry brown materials such as leaves, sawdust, hay, and branches. These materials are high in carbon, but they break down very slowly. There are also green materials like vegetable peelings and lawn clippings which break down faster and provide nitrogen. To balance both brown and green matter and boost nitrogen content in your compost, you can add undiluted urine. Doing this helps in balancing the ratio of nutrients besides accelerating the breakdown of the matter. 

Deterring Animal Invasion

Human urine has a pungent smell that can deter wild animals from invading your farm. Animals such as deer, rabbits, cats, and foxes may not like the strong smell, which could act as a defense for your farm. You can therefore consider peeing in your backyard if you experience the problem of wild animals destroying your crops. 

Besides peeing in the garden, you can also fill a watering can or spray bottle with this liquid and spray it around your garden on bushes or trees where the animals can smell it. 

What Are The Benefits Of Using Urine As A Fertilizer?

Using urine as a fertilizer has several benefits, especially on maize, onions, and leafy green vegetables. These benefits include;

  • It is an excellent source of phosphorous, nitrogen, potassium, and trace elements essential for plant growth. 
  • It is non-toxic to plants besides being a body waste
  • The liquid is sterile when fresh and, therefore free from bacteria

Is It Safe To Use Urine As A Fertilizer?

Yes, using urine as a fertilizer can be safe and beneficial for plants when done properly. Urine contains essential nutrients like nitrogen, phosphorus, and potassium that can nourish plants. However, it’s crucial to dilute urine with water (usually 1 part urine to 10-15 parts water) to avoid harming plants with excessive salts and high nitrogen concentrations. Additionally, it is best to use urine from healthy individuals, as certain medical conditions or medications may render it unsuitable for use as fertilizer.

When not to use pee As A Fertilizer?

There are certain situations when using urine as a fertilizer is not advisable:

  1. When urine is contaminated: If the urine contains traces of medications, chemicals, or toxins due to certain health conditions or medications, it should not be used as fertilizer as it may harm plants and soil.
  2. Fresh urine on sensitive plants: Fresh, undiluted urine can be too strong for sensitive plants, potentially causing damage to their roots or foliage.
  3. Edible crops: Urine should not be used as a fertilizer for edible crops, especially those consumed raw, to avoid potential health risks from pathogens present in urine.
  4. High salt content: If you have a high-salt diet or certain health conditions that lead to excess salt in your urine, it is not suitable for use as fertilizer, as it can harm plants and soil.
  5. On acidic-loving plants: Urine is naturally slightly acidic, so it may not be suitable for plants that prefer alkaline or neutral soil conditions.
  6. In areas with restricted water supply: Using urine as fertilizer requires dilution with water, and in regions with limited water resources, this practice may not be practical.

What Does Human Urine Consist Of?

Human urine consists of about 95% water, and the remaining 5% is a mixture of salts, minerals, enzymes, hormones, and urea (around 2.5%). The following table shows some of these components and their percentages. 


Percentage composition (%)
UreaAround 2.5
Potassium 0.6
Uric acid0.03

How Can You Use Urine On Plants?

You can use urine in various ways, such as applying it in solution form to plants. Doing this helps to boost plants’ growth. Since urine is too strong to use undiluted on most plants, you can dilute it as follows;

  • Add 10-15 parts of water to 1 part of fresh urine and apply on crops in the growth stage.
  • Mix 30-50 parts of water and 1 part of urine and apply on plants sensitive to fertilizers and growing in pots.

Avoid using urine daily on your plants since too much of it could be harmful even when diluted. You can use this product on plants that require a lot of nitrogen, such as tomatoes, cucumbers, corn, and squash. Be sure to use it when these crops are in their fruit-bearing stage for better production. 

Urine is also advantageous to use on crops that show nitrogen deficiency, resulting in pale green and yellow leaves. Make sure that you don’t apply too much of this substance that would lead to excess nitrogen. Too much nitrogen may lead to your plants becoming bushy and leafy, which can attract aphids, and the plants may also bear fewer fruits. You can tell that your crops have excess nitrogen if their leaves become curled. 

What Are Some Health Precautions To Take While Using Urine On Crops?

Since urine is a bodily waste, you need to observe some health precautions when using it on plants. They include;

Avoid Contaminating The Liquid.

Ensure that the urine you use on plants is safe by preventing contamination with other body wastes such as feces. You can put your urine in a plastic jug or use special toilets that separate the urine and direct it to a storage tank. You may also store the solution in sealed containers for several months to reduce any potential pathogens. 

Do Not Use Urine From An Infected Person.

If a person is on medication or has a urinary tract infection, their urine should not be used on edible crops. But, one can use the urine on landscaping or lawns to prevent it from getting into contact with aquatic environments. 

Giving It Time

It will be safe to wait for a while (about one month) after applying the urine on edible crops before eating the same. It is also advisable to use your urine more than other people’s to avoid infections if any. 

Storing Urine From A Group Of People

If you are mixing urine from a group of people, it is necessary to preserve it first since there are many chances of pathogens. Make sure that you store this product in a sealed container for six months before using it. You will also need to wait for another month after applying on the crops before eating the same as an extra precaution. 

Be Extra Careful

You can use urine as a fertilizer on fruit-bearing crops such as cucumbers and tomatoes for social acceptability and safety concerns. You can also use it on perennials like trees and bushes with then use the leaves in a compost pile. You may also use the leaves as mulch since this is a socially accepted and safe method to cycle the nutrients back into the garden. 


While urine can kill plants if undiluted and if used in excess, it benefits the crops. Urine contains a lot of water which is advantageous to the crops, as well as essential nutrients. Using urine as a fertilizer will provide the plants with nitrogen, phosphorous, and calcium necessary for plants growth. 

When diluting the urine, it is vital to make sure that you add the right amount of water to prevent it from harming your crops.