It was not what you expect in a party gift.

Hundreds of guests showed up this spring for Plant Nerd Night, the hot-ticket event on the Portland gardening calendar. Some arrived hours early to camp out for the chance to see radio green thumb Mike Darcy, a dazzling lineup of 12-minute plant presentations and the Goddess Flora Chorus and Deadheading Society performing its '60s-themed showstopper, "The Age of Asparagus."

But when guests peeked into their hard-won swag bags, they found an apparent coal-in-the-stocking stuffer: a plastic sack of dust.

Puzzled emails among some of the Portland area's 2,000 Hardy Plant Society members soon gave way to intriguing anecdotes of a natural fertilizer yielding big, "science-fiction-like results" around the city's urban-farming culture.

Soon they realized that what they had was a sample of the latest and most inexpensive elixir for growing edibles: glacial rock dust. It was supplied by a thriving, below-the-radar local institution, Southeast Portland feed store Concentrates, the go-to place if you're running a little short on bat guano or feel your life would be better with a fresh batch of beneficial bacteria.

"We're kind of a secret society," general manager Heather Havens says.

Most Portlanders aren't aware of it, but Concentrates describes itself as the largest organic fertilizer distributor on the West Coast, driven by sales of its Gaia Green glacial rock dust, which have more than tripled in the past five years, owner Bill Sparks says. In the past year, he's sold 151 tons of the dust, a natural byproduct of ancient glacial moraine rocks mined in coastal southwestern British Columbia.

Concentrates is no secret among the professional urban farmers who grow the toothsome vegetables, herbs and fruits that Portlanders relish in locavore-inflected restaurants such as Noble Rot and Meriwether's. Marc Boucher-Colbert, who farms the pioneering rooftop food garden for Noble Rot, says he uses about 100 pounds of glacial rock dust a year from Concentrates. He believes its array of 67 minerals helps plants grow more vigorously, perhaps more nutritiously, and stand up better to frost, extending his growing season.

Boucher-Colbert became a customer after founding the educational and environmental Urban Bounty Farm in 1993. Back then, Concentrates was run by an edgier band of fellas, whom Boucher-Colbert and other farmers jokingly called "the pirates." This was during an era when Havens recalls the forklift used to occasionally fall through the rotting floor of their former warehouse.

The newer, "tidied-up" edition of Concentrates two blocks away, like its signature product, is making word-of-mouth inroads year by year with Portland's ordinary foodies and gardeners. Many have moved away from conventional chemical fertilizers, which tend to be synthetic and petroleum-based products, to experiment in their yards with the gentler, less-processed world of organic plant, animal or mineral-based fertilizers from local or regional sources. These natural materials are in favor because they build a more inviting soil community for the microbial labor force of good-guy bacteria, fungi and worms that support healthier plants bound for the gardener's own plate.

With the homemade ethos penetrating every corner of Portland, making your own organic fertilizer—if you can tear yourself away from your compulsive crafting—is a path to vegetative virtuousness and curbside cred. Folks who hit Concentrates can buy the four to six raw materials to mix their own fertilizer. Those who prefer others to do their handiwork can just buy a similar sack of premixed natural fertilizer, which includes a heaping helping of glacial rock dust.

Concentrates sits close-in, at the foot of the Ross Island Bridge, yet new customers may feel they've wandered into a Wilco video with the lonely grain elevator and the phantom painted lettering for the lost Darigold Dairy Co-op. An odd, peaceable kingdom of work pickups and Lexus SUVs nose up at a loading dock adorned with a rustic chalkboard. On inspection, it reveals lusty personals ads for urban livestock dating. ("Pygmy goat stud service $20/I will deliver or keep your doe at my place.")

The warehouse door exhales forklifts and mysterious, earthy aromas, which are made up of most everything that can go in or come out of an animal, along with a few things you just apply to the outside. Concentrates leans hard to the organic and sustainable, but Havens carries conventional fertilizers for elder farmers who've been customers for 50 years. "I'm not going to tell my favorite old guy he can't have his 16-16-16," she says.

The glacial rock dust, for the record, is odor-free, not that we're judging. You can use it by itself, and it's gently idiot-proof—you can't do a plant, or watershed, harm by overapplying it, unlike synthetic fertilizers. Best of all, it's astonishingly inexpensive at $11.80 for a 50-pound bag. That means Boucher-Colbert, who uses it in concert with other organic nutrients, spends only about $20 a year on glacial rock dust to mineralize the whole Noble Rot restaurant garden. But be forewarned: It's a gateway drug to harder organic fertilizer use.

And there is a downside to its surging popularity: Retailers and wholesalers, including Concentrates, lament periodically running out, especially in the spring.

On the other hand, that's made Havens' ordering routine with supplier Gaia Green extremely simple—"I told them: 'Just keep sending trucks till I tell you to stop.'"


One of rock dust's earlier adherents and promoters is Bob Cannard, the Petaluma organic farmer known for raising the "designer vegetables" for Alice Waters' Chez Panisse.

GO: Concentrates, 2613 SE 8th Ave., 234-7501,