A little urine now and then won't damage a garden. But repeated soakings of human or animal pee can kill plants. Credit: Courtesy of Debbie Eustis-Grandy

Sometimes you can’t help it: a wild animal wanders near your precious kitchen garden and urinates. Or the family dog raises a leg on the tomatoes you have been carefully cultivating.

Is it the end of your carefully tended food? No, experts say. But you do need to take steps to ensure your safety — and to prevent contamination in the future.

Beyond the obvious ick factor, urine can damage plants, as well as cause health problems for both other animals and humans.

Here’s what you need to know.

How urine impacts plants

With so many critters looking for places to pee, some of them are inevitably going to relieve themselves in your garden. But a little bit of urine from time to time hitting your soil or plants will not damage them. The problem comes when one or more animals makes a constant habit of using your garden as its own public restroom.

All urine contains nitrogen, something your garden needs in moderation. Too much nitrogen burns growing plants and overpowers beneficial soil compounds. That’s why you see brown patches of dead grass on lawns where dogs frequently pee, for instance.

It’s not just dog pee, too much concentrated urine from wildlife like foxes, deer and moose can pollute the soil and discolor, injure, or severely damage growing plants.

Likewise, you should keep human urine out of the garden too. While there have been some studies on using human urine as both fertilizer and a wildlife deterrent in gardens, experts caution against it.

“The idea behind it is that [human] urine does contain some level of ammonia and that is known to have some repellent qualities,” said Jim Dill, pest management specialist at University of Maine Cooperative Extension. “But to have the level of ammonia needed to keep deer away the person would have to be fairly dehydrated or have some other form of a medical condition.”

What’s the risk?

While there are no toxins harmful to humans found in animal urine, there can be disease-causing bacteria, viruses, fungi or parasites lurking in the urine and feces.

Animal droppings, for example, can contain pathogens that cause toxoplasmosis, E. coli and salmonella. There also can be parasites that cause giardia and cryptosporidium. In addition to roundworms, hookworms and tapeworms — all of which are happy to take up residence in the human gastrointestinal system and make you very sick.

Leptospirosis also can be transmitted via contaminated soil or water inhaled, ingested or exposed to open wounds.  

Because all of these dangers can jump from animals to humans, they are known as zoonotic diseases.

“Bringing your pets to the veterinarian for regular exams, vaccinations and deworming is important,” said Dana Hill, director of the veterinary diagnostic laboratory at the University of Maine. “These are important to prevent zoonotic disease.”

What should you do if pee gets on your edible plants?

Your best bet is to always assume that something has gotten on your edible plants. That’s why you should never eat anything from your garden before washing it. The food safety experts at University of Maine Cooperative Extension recommend washing vegetables in clean, room temperature water.

Use a vegetable brush to scrub anything with a thick skin. For veggies with nooks and crannies like cauliflower, broccoli or lettuce, soak for one to two minutes in cool, potable water.

For the leafy greens, you can drain them in a strainer or colander and then dry them with a clean towel or salad spinner.

The best thing you can do is stop it from happening

They say that good fences make good neighbors — but good fences also make safer gardens by keeping animals away from edible plants.

A fence at least six feet tall with a two-foot overhang will help keep household pets out. Since dogs are good at digging, an additional foot or two of fencing should be underground, or the perimeter can be lined with rocks.

Since your garden will likely need to be watered, you can set up motion-activated sprinklers. A blast of water may be enough of a deterrent to chase dogs and cats away and keep them from coming back.

Anything that smells strong can help keep dogs out. Try soaking cotton balls in ammonia, rubbing alcohol or vinegar and sprinkling them around the border of your garden. Sprinkling common chili powder around it can also repel dogs.

Julia Bayly is a reporter at the Bangor Daily News with a regular bi-weekly column. Julia has been a freelance travel writer/photographer since 2000.