Fertilizer made mostly from elephant dung seems to be the latest craze among gardeners since the pandemic prompted a heightened incentive to grow things.

Nicknamed “zoo doo,” it is distributed free by the bucketful at the Honolulu Zoo, which has two elephants on exhibit.

Zoo Director Linda Santos said when the pandemic required people to stay home, they had a lot of time on their hands and the demand for zoo doo exploded.

“All of a sudden, everyone wanted to garden!” she said. “We had such a high demand for compost, we couldn’t supply enough for the public, so we had to take reservations.”

The zoo first offered the compost on Oahu in the late 1980s and ’90s, and only schools, community gardens and a few individuals were interested, she said. The zoo uses much of the compost for its landscaping and other projects, so there’s not a lot of excess.

Santos is quite surprised at how the product’s popularity spread through word of mouth and social media, particularly through the 808 Green Thumbs Facebook page. Everyone told their friends, and people started calling the zoo more frequently, she said.

Zoo doo comprises 30% elephant dung, mixed with poop from giraffes, zebras, hippos, mini-horses and other animals that have plant-based diets.

“Elephants obviously make the biggest poop, so a lot goes a long way!” said Santos, laughing. “And obviously, it’s a huge bolus (mass of chewed food) if it doesn’t break down. They have poor digestive systems, so what goes in comes out like a ball of hay.”

Of course, the supply is endless since poop is ­collected daily, though she isn’t sure how many pounds of poop piles up on a given day. (The International Elephant Foundation estimates that elephants produce 220 to 250 pounds of dung a day.) The groundskeepers will add dried leaves and other plant debris to it, and keep turning it over and watering it until it breaks down properly.

Head groundskeeper ­Anthony Pa gives out some compost every Saturday between 8 and 11:30 a.m. by appointment, and normally schedules about 56 pickups per month, Santos said. The public isn’t allowed into the compost area but can park their vehicles nearby, and staff will fill their buckets for them.

The zoo doesn’t charge a price for the compost because it isn’t regulated or tested, and thus, Santos doesn’t know the percentage of its macro-nutrients, such as nitrogen or phosphorus.

But advantages of zoo doo, according to the Green Living Guide, are that it’s a synthetic-free, nutrient-rich fertilizer option, which prevents chemicals from getting into the ground and water, and reduces the amount of waste going into landfills. Manure from animals whose diets include that of animal origin isn’t used in compost because it might harbor harmful bacteria that could spread disease. (See 808ne.ws/zoodoo.)

Justin and Grace Lin started picking up zoo doo a year ago to give away at their “free store,” which is set up in front of their ­Hawaii Kai home. Through the 808 Green Thumbs Facebook page, they learned about zoo doo and an informal network of about a dozen garden-­based free stores on Oahu, organized by nomoola.com.

Once the pandemic started, the Lins decided to increase the amount of vegetables and plants they grew as part of a home-­schooling project for their three young daughters. The family shares them with neighbors through the free store, in addition to offering an exchange library. Justin Lin said he picks up about 8 to 10 (5-gallon) buckets of zoo doo every two weeks. At home, his girls, ages 4 to 6, help bag the compost. They put 3 to 5 pounds in 10-gallon trash bags, and they aren’t hesitant to handle it because it doesn’t smell, he added.

After they announce the supply on the Green Thumbs page, “more times than not, three to five people are waiting for it,” he said. He puts out 15 bags at a time, and a couple days later, another 15, and they’re gone by the end of the days. “It’s a crazy phenomenon! I have to limit people or they’ll try to take as much as they can.

“The zoo doo is extremely fertile and has a lot of nutrients. Everywhere we need it, stuff has grown abundantly,” said Justin Lin. “Some people grow things with straight zoo doo (no dirt); it works really, really well.”

Picking up and bagging the compost takes some time and effort, but it’s worth it. His daughters benefit from learning about life cycles, and the community finds out about new things along the way.

“It feels good to be able to share,” he said.

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Zoo doo

>> The Honolulu Zoo has a very limited supply of zoo doo available to the public. If you would like to be put on the waitlist, you can email the zoo at Tpa@honolulu.gov.

>> You might also find postings about local free-store offerings of zoo doo on the 808 Green Thumbs Facebook page at facebook.com/groups/808greenthumbs.

Is there a gardening topic you’d like to read about in the Garden Variety column? Email Pat Gee at pgee@staradvertiser.com with your request.