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Riding the Mushroom Boom

Small-Scale Growers Seek
Niche in Cultivation of Exotics

Producing Button Mushrooms En Masse
The Tricky Art of Growing Shiitakes

By Diana L. Meredith

Dean Hanson of Kingsburg used to pick wild mushrooms as a hobby. One time, he said, he accidentally picked the wrong ones and fed them to his brother -- an attorney -- who promptly got sick. Oops.

Dean Hanson and son

Not too long ago, most shoppers knew only two varieties of mushrooms: fresh white buttons and canned white buttons.


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Photos: Susan McLearan

"Since I had always been fascinated by mushrooms, I decided I better get more information about them," Hanson said with a laugh.

A former beauty salon owner, Hanson took a course in mushroom cultivation and with his wife Kathy started a small business three years ago, growing shiitakes, oyster mushrooms and portobellos. They sell their crop at the Fresno Farmers Market. At least once a week, Hanson said, he gets asked, "are these poisonous?" Hanson responds, "Yes, the county sent us here to poison you." Everybody laughs, and the patron usually buys some mushrooms.

Hanson’s story illustrates the unique challenge of selling exotic mushrooms for a living. The fact that he can make a career of it reflects the growing consumer interest in fresh mushrooms. Overall, U.S. production has soared nearly five-fold in the last 30 years to 778 million pounds in 1995-96, according to figures from the United States Department of Agriculture. And the proportion of the harvest consumed fresh has grown from 25 percent to 69 percent in that period of time.

Yet most consumers still don’t have the foggiest idea what to do with them. "There are only so many people who eat mushrooms," Hanson said, who is the only grower of exotic mushrooms selling at the Fresno market. Another grower tried to gain a foothold but gave up after a few months. Hanson was already meeting all of the demand.

More than 60 percent of Americans either don’t eat mushrooms or eat them only occasionally, said Wade Whitfield, executive director of the Mushroom Council. About 25 percent of the population are moderate users of mushrooms, and 11 percent are heavy users. All but writing off the nonusers, the council seeks to increase demand by convincing moderate mushroom users to boost their consumption.

Not too long ago, most shoppers knew only two varieties of mushrooms: fresh white buttons and canned white buttons. The familiar variety still dominates the U.S. market, accounting for 90 percent of the total fresh mushroom crop last year. But that is down from 95 percent three years ago, according to the Mushroom Council, an industry promotion association.

While they account for a minuscule portion of the total mushroom market, the more exotic varieties are experiencing the most rapid growth. According to the USDA’s 1996 Mushroom Report, production of exotic varieties reached 8.84 million pounds in 1995-96, with shiitakes accounting for 85 percent of that total. But the harvest of "other exotics," ranging from the wood ear to the bear’s head, was up 53 percent from the level of just two years ago.

The press is helping encourage consumption of a greater diversity of mushrooms. Newspaper food sections and popular cookbooks these days sing the praises of the shiitake, the enoki mushroom and other varieties that were unknown just a few years ago.

For farmers, mushrooms are a tempting crop because of the high price and potentially high yield. They have a short life cycle and can be grown year-round, so they can be harvested continuously.

Dr. Mo-mei Chen, a Chinese mycologist who has been a visiting professor at the University of California at Berkeley, regularly offers courses on mushroom cultivation and has inspired many to try their hand at it, including Hanson, who is one of her former students. Anyone can grow them, she says, though she cautions that producing mushrooms commercially presents a new set of much tougher challenges.

To begin with, most mushrooms don’t submit at all to cultivation. While 300 species of mushrooms are edible, only about 30 have been domesticated and only 10 of those can be produced in batches of more than a pound or two. The biggest challenge for small-scale growers, particularly those who intend to sell at farmers markets, is to maintain consistent production. Since everything from the humidity in the air to the quality of the growing medium can affect yields, keeping all variables constant is a delicate balancing act. A variety like the shiitake can be cultivated with great success, but beginners are bound to botch the first couple of crops, she said.

Large-scale growers have certainly perfected the art of button mushroom production in the last couple of decades. According to USDA data, button mushroom yields increased from about 2 pounds per square foot annually in 1967 to 5.75 pounds per square foot in 1995-96. Meanwhile, the six largest mushroom producers in the nation have grown to account for 50 percent of total U.S. production, according to the Mushroom Council.

Now, the mass production of button mushrooms may be pushing medium-sized producers into niches once filled by mom and pop growers. The Petaluma Mushroom Farm, for one, after 25 years in the button mushroom business, plans to start cultivating shiitakes and oyster mushrooms next year, having added portobellos to the lineup last year.

The company for years has sold exotics grown by other farmers. But demand from existing customers increased to such a point that the company decided to start its own production, said Jerry Fisher, sales and marketing manager for Petaluma Mushroom, which has 75 full-time employees and occupies 25 acres on a converted chicken farm on the outskirts of Petaluma.

The company sells most of its production to wholesalers. But the company’s employees sell Petaluma Mushroom Farm’s white mushrooms, brown mushrooms and portobellos at farmers markets, as well.

The large-scale, year-round production at Petaluma Mushroom Farm calls for a lot of electricity, specialized equipment and hand labor. The production process there starts with a compost of used straw from a horse racing track. A machine lays compost and peat into 4’x 8’ bins.

After watering, the mushroom spawn (obtained from spawn companies) is mixed into the compost. The bins then spend one week in a steam-heated room where the temperature hovers between 110 and 130 degrees Fahrenheit. After the addition of more peat moss, the bins spend two weeks in another, cooler room, until they are finally transferred to windowless growing rooms.

The white mushrooms grow in complete darkness, the browns and portobellos grow in weak light. The bins spend three weeks in the growing rooms, where the mushrooms are harvested gradually. The entire cycle, from laying compost in the bins until the last mushroom is picked, takes six weeks (portobellos take longer). Throughout the process, employees monitor air temperature, soil temperature and humidity. Unlike many crops, the mushrooms are watered and harvested entirely by hand.

Petaluma Mushroom achieves a lower yield per square foot than the major corporate growers. But the company prefers to trade high yields for better quality, Fisher said. As a result, its mushrooms cost more than the generic ones available at the supermarket, but some customers are willing to pay the difference for a superior product, Fisher said. Consumers who shop at farmers markets are especially quality-conscious, he said. "They want to know it’s fresh, and they want to know it’s good. They are looking for things you just can’t find at the supermarket."

The production process for shiitakes, oysters and other exotics is different. In the wild, they grow on trees rather than in the ground.

Under cultivation, shiitakes grow in special plastic bags filled with oak chips. The growing medium must be inoculated with the shiitake spawn in a sterile laboratory environment, which makes shiitake-growing a very meticulous process.

Oyster mushrooms, on the other hand, "are easy," Hanson said. He mixes spawn with straw and puts the straw in plastic bags with slits. A few weeks later, he has mushrooms.

Hanson said the cost of inputs for exotic mushroom growing, especially electricity, can be minimized if growers cultivate seasonally appropriate strains of mushroom. Growing different strains, however, requires more work. It also creates a marketing challenge, because the various strains of oyster mushrooms, for example, all look different, he said.

Hanson added that he has had a hard time convincing other growers to produce in harmony with the seasons. Even with the added cost of climate control, the profit margin on exotic mushrooms is still substantial.

But Hanson, an advocate of sustainable agriculture, practices what he preaches. His mushrooms grow in a barn where the only electrical devices are a fan and a 40-watt light bulb. He and his wife supply all necessary labor.

Growing exotic mushrooms is a challenge that apparently many people want to take up. Whitfield, of the Mushroom Council, said he gets calls all the time from people interested in growing exotic mushrooms. He gives them all the same advice: "If you’re going to get into the growing business, it’s going to cost you some money. But the first thing you want to be sure of is that you have a place to sell them," he says.

The farmers markets has been an ideal outlet for Hanson, but he hopes to expand into the wholesale business once his production is large enough.

He is optimistic about the prospects for himself and other small-scale mushroom producers. "There are a lot of different niches that a person can go into," Hanson said. He knows small growers who sell to restaurants and to the big mushroom companies, which have traditionally filled out their needs for mushrooms by buying from small growers. As long as "If you grow a good product, you can market it," he said.

Copyright 1997 In Season