Dan Olson of Minnesota Public Radio visits Forest Mushrooms

Kevin Doyle tells mushroom stories the way anglers talk about landing the big one.

Once, during a walkabout on his farm, he came across a giant grifola frondosa, or hen-of-the-woods mushroom. "It looks like a hen with its feathers ruffled up," he recalled excitedly. "The biggest one I've picked is 38 pounds. They're huge."

Mushrooms have been very good to Doyle. What began more than 30 years ago as a way to make a living off his natural sciences degree has, well, mushroomed into a huge indoor farming operation growing 3,000 pounds of mushrooms a week, year round, on 20 acres of rolling, forested hills in Stearns County that once housed the St. John's Abbey hog farm.

Forest Mushrooms is now the state's largest mushroom grower. Doyle, 58, and his 11 full time employees grow two kinds of mushrooms: the relatively bland tasting oyster and the more distinctive shiitake.

And while the product is a fungus, a recent walk through the operation shows it's more like a clean room with the smell of a forest floor. The rooms are washed constantly, well lit and clean, with a temperature of 65 degrees and 93 percent relative humidity.

The mushrooms sprout from pasteurized rounds of straw or sawdust. The rounds run about the size of a big bread loaf and they're laced with organic nutrients.

Fresh air to help the oxygen-gulping fungi grow gushes through nozzles from a plastic tube suspended from the ceiling of the growing rooms. The air from the outdoors has been humidified and heated or cooled depending on the season, with water droplets removed. Doyle says the cellulose and lignin digesting mushrooms consume oxygen and emit carbon dioxide.

Doyle did not set out to be a mushroom magnate, but he did have a love for all things natural.

There was no TV in his house growing up. Instead Doyle's parents supplied him and his seven siblings with lots of books for reading, catering to their interests. He remembers long rambles over hill and dale. "The outdoors was my TV...and it was a big adventure to just go out and walk through the woods."

Doyle finished college at St. John's University with a bachelor's degree in natural science, which included botany courses.

He landed a job as a University of Minnesota researcher, exploring alternatives to fossil fuels as oil prices spiked. But as oil prices stabilized Doyle guessed the federal funding for alternative fuels research would decline and he'd soon be out of a job.

He began exploring other lines of work.

He remembers stepping into an office lobby as he waited for a friend to join him for lunch and leafing through a National Research Council journal he found on a nearby table devoted to economies in developing countries. There along with the other articles was a short chapter on mushroom growing.

Doyle says his curiosity led him to other publications explaining how to grow mushrooms in mediums made of straw and sawdust, both abundant in Minnesota.

He landed a job in a central Minnesota cabinet making business but the mushroom growing idea stayed with him and was fueled over beers with a grad student friend, who needed to create a hypothetical business for a course assignment.

Doyle suggested a mushroom business. This was about 1983, he recalls, and with his friend's input Doyle began amassing a library about growing mushrooms and learned there was no one else he could find in Minnesota who was doing it.

He enlisted friends from his college days to join him as partners in a mushroom business. He says some training in drafting helped him create small tables for raising the fungi, and they started their operation in the basement of a home in Ham Lake, where he and the partners harvested mushrooms and sold directly to Twin Cities restaurants.

Doyle says he was 27 years old and self taught, never having taken a business course. He eventually bought out his partners and moved on.

Minnesota, he says, is a wonderful state for mushrooms — he counts 14 varieties that are edible — but with a very short season. If you want them year 'round you need growing rooms, like the ones on his mushroom farm.

Besides growing the fungi, Forest Mushrooms is also one of the state's largest wholesale distributors of mushrooms grown elsewhere. He says they package and distribute through food wholesalers as many as 20 varieties of mushrooms from Oregon, Washington, British Columbia and other areas.

Ever watchful for new opportunities, Doyle has a sideline operation recycling the already recycled sawdust and straw after the mushrooms are harvested.

"When we're done with it, it ends up being sold to local gardeners for a mulch for their gardens," he said. "Some of the people who have used it for 20 or 25 years since we've been here, said it's made a tremendous difference in the quality of their soil ... they love it because the fungus has already done a lot of the degradation."