How To Use Your Pee For The Planet

Discover the incredible benefit of this free resource.

August 18, 2015
man spraying son with hose
PHOTOGRAPH BY JOHN HOWARD/GETTY

Depending on which gardening circles you hang with, the concept of urine in the garden may already have surfaced as a discussion topic. So what's the deal? Should you seriously pee on your peas, tinkle on your tomatoes, and take a leak on your lettuce?

Related: Is People Poop Good For Plants?

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Well, not on them, exactly, but if you aren't using your urine in your garden and on your compost pile, you are, pardon my French, pissing away a free, valuable resource and missing out an easy way to help close the gaping hole in your household nutrient cycle. Using urine in the garden can help you cut your water use (less flushing) while also cleaning up the environment downstream (no water-polluting fertilizer runoff).

Your #1 Choice For Fertilizer
Recent scientific studies have shown urine is a safe and very effective fertilizer for cabbage, beets, cucumbers, and tomatoes, and pretty much anything else you want to grow. Urine boasts a nitrogen-phosphorus-potassium (N-P-K) ratio of 10:1:4, plus more modest amounts of the trace elements plants need to thrive. The nutrients in pee are highly available to plants, too—an extra plus. One estimate suggests a family of four can produce the equivalent of more than 100 pounds of all-purpose garden fertilizer every year. Oh, and the best part? It's free! Oh, be still, my nickel-pinching heart!

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But ewwww...yuck! Is it safe? Yes! Unless you have a serious infection, urine is usually sterile, and the chances of disease transmission from it on the household level are very, very small. And any slight odor dissipates almost immediately once it's applied to the soil. While we're not suggesting you drink your urine, know that astronauts on the International Space Station do drink the stuff—after it's purified. So comparatively speaking, sprinkling it on the soil in the garden is a pretty tame use.

How To Use Your Very Own Garden Gold (Free Deliveries Daily!)
Depending on your personal plumbing arrangement (guys have the edge here) and the privacy of your garden, you may be tempted to deliver the product to the soil directly. But in most cases, the concentration of nutrients could be too great, which can damage soil microorganisms and burn plants. Direct application is fine, in moderation, for compost piles (especially if you have loads of dry brown, high-carbon materials like fallen leaves, straw, or shredded paper that are crying out for nitrogen) and for straw bales being conditioned for use as planters. 

Otherwise, it's best to collect the raw product in a container with a lid, perhaps with the help of a funnel or a "nuns cap" (a plastic contraption hospitals use to collect samples, which makes it easy for gals to contribute while sitting on the toilet as usual). Experiment until you find a system that works easily for you. Once a day or so, empty the accumulated urine into a watering can, dilute it with 5 to 10 parts of water, and sprinkle the mixture onto the soil around your plants, avoiding getting it on the plants themselves—especially the parts to be eaten—as much as possible. Rotate where you're applying golden irrigation so that all your plants get a turn every so often.

Related: Deter Garden Bugs Naturally

Apply diluted urine to the soil only when the soil itself is at least 50 degrees Fahrenheit. At that temp, the soil microbes will be active and ready to soak up the nitrogen and other nutrients. In colder weather, you can either go back to flushing your urine down the toilet or stockpile your liquid gold in tightly closed containers (if you have the space and the inclination). Storing in closed containers for a couple of weeks is also a good way to kill off any potential pathogens if someone in the family has been sick. 

Add Ashes For More Flowers, Fruits, + Roots
The high nitrogen content of urine makes it perfect for seedlings and leafy crops, but the low potassium content leaves it a bit skimpy on the stuff that flowers, fruits, and roots need. But we can fix that for free, too: Finnish researchers discovered that adding wood ashes to urine fertilizer for tomato plants resulted in sweeter fruit—and four times as much fruit! Adding wood ashes also boosted beet root size. This makes sense, since wood ashes have an N-P-K ratio of about 0:1:3, plus a lot of calcium. A handful of sifted wood ashes (save the chunks for the compost bin) will boost the potassium level in a bucket of liquid gold very nicely.

You can also sprinkle a handful of wood ashes over every 2 to 3 inches of new organic matter in the compost pile. But don't go overboard: Ten to 15 pounds of wood ash a year is enough for a 1,000-square-foot garden. And if your soil is very alkaline, wood ashes might not be the best choice, as they make soil even more alkaline. Be sure to only use wood ashes from untreated wood (hardwoods' ashes have the most potassium), avoid burning large amounts of glossy paper, and never, ever use coal ashes

A Note On Salts
Urine contains significant levels of salt, which can build up in the soil in containers or even in garden beds when the climate is dry, injuring plants. Salt damage can show up as scorched-looking leaves; wilting, even when soil is moist; and stunted growth. There may even be a whitish crust on the surface of the soil. You can reduce salt buildup by watering generously (enough so that water runs out of the bottom of the pot after the soil is completely saturated) at least once a week.

Taking It Up A Notch
In Europe, where a lot of research is focusing on closing the nutrient cycle and decreasing environmental costs, you can purchase a standard-looking toilet that has a urine diversion bowl, which makes the entire collection process hands-off. In some areas, you can even contract with a service to come and empty the tank periodically and deliver your accumulated urine to an appreciative farmer. While less of that is going on in the U.S., urine diversion toilets are available through specialty plumbing supply houses if you want to make the investment. And if you live near Burlington, Vermont, the Rich Earth Institute is actively researching the collection and use of urine as a fertilizer and is looking for donations. The Institute's website offers good advice on collecting urine in general.

Fans of bathroom poetry (I must confess I am one) will recognize the ditty, "If it's yellow, let it mellow," to which I say, let's change it to: "If it's yellow, grow a tomato!"

This article was originally published on RodaleWellness.

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