While certified organic mushrooms make up only a fraction of the market, their numbers continue to grow.

Last year, 22.6 million pounds of U.S. mushrooms were sold as certified organic, said Laura Phelps, president of the Washington, D.C.-based American Mushroom Institute.

“That’s up 8% from the previous year, a pretty big jump,” Phelps said.

Joe Caldwell, vice president of Watsonville, Calif.-based Monterey Mushrooms, said organic may be growing faster than nonorganic mushrooms, but it’s still only about 3% to 4% of the total.

“Still, it’s going to continue to grow, and we see that trend continuing for the foreseeable future,” Caldwell said.

All mushrooms are almost organic, he said. Though few chemicals are used on the beds, synthetic fertilizers may be used in making the compost the mushrooms grow in.

Meg Hill, director of sales and marketing for Sebastopol, Calif.- based Gourmet Mushrooms Inc., said the growth of Gourmet’s organic specialty mushrooms has been “startlingly high” in the past year.

She wonders if it’s a reaction to Japan’s 2011 nuclear disaster at Fukushima, or if consumers are simply more concerned about what’s in their food.

“I think the world is shifting enough that organic growth is guaranteed,” said Hill. “Our price point is high, and our growth is incredible. No one says we’re too expensive. Either they want it or they don’t.”

Rick Watters, sales manager of Champ’s Mushrooms Inc., Aldergrove, British Columbia, Western Canada’s largest mushroom distributor, said organics represent 8% to 10% of Champ’s market.

“It has remained fairly steady in the past few years, and we’re not seeing more demand,” Watters said.

On the East Coast, Peter Wilder, marketing director of Avondale, Pa., To-Jo Fresh Mushrooms Inc., said he hasn’t seen enough demand from customers to warrant the big step of seeking certification.

“In general, mushrooms are all natural, they’re healthy and they’re pretty much organic — we’re just not organically certified,” said Wilder.

Bill St. John, sales and transportation manager for Gonzales, Texas-based Kitchen Pride, said most people can name half a dozen items they’d buy as organic, and mushrooms aren’t on the list.

“It’s a small part of the market, and it’s more expensive,” he said.