Chris Pacheco is the mushroom man. 

“I left corporate America to become a farmer, a mushroom farmer. Who does that?” asked Pacheco, the owner of Mystic/Stonington-based Seacoast Mushrooms who spent 15 years as an engineer at biopharmaceutical giant Amgen after a stint in the Navy.

Today, Pacheco grows shiitakes, maitakes, lion’s mane, pioppinos, king, blue and golden oyster mushrooms, as well as other varieties, in recycled insulated, refrigerated shipping containers that he has repurposed as growing rooms.

Most commercial mushrooms — the creminis, whites and portobellas — are grown in manure. But Pacheco’s produce is part of a growing trend, what are called gourmet mushrooms, like those that grow outdoors naturally.

Walk inside one of his growing rooms, and a cool mist envelops the floor-to-ceiling racks of mushrooms sprouting from oversized plastic bags called blocks. The bags were stuffed with a sawdust, millet, bran, and crushed oyster shell mixture and sterilized in an autoclave before spores were added.

“We take a sterilized bag and introduce spores to the bag,” said Pacheco. “Then we seal the bag and let those spores turn into mycelium that grows through the sawdust and binds all the material together to make these blocks.”

The growing process, he said, is science-driven. The full bags, or blocks, are the substrate. He has mimicked how wild mushrooms grow in the forest and speeded up the process. 

In three to four weeks, Pacheco can do what takes two years in the wild. In his grow rooms, his mushrooms double in size every single day. In a week, one grow room may produce 600 pounds to 800 pounds of gourmet mushrooms.

In the blocks, spores that have begun to spawn transition to mycelium, which consumes the nutrients — the bran and millet — and creates carbon dioxide as part of a fermentation process. Growing mushrooms requires precise temperatures, 12 hours of daylight provided by overhead lamps and fresh air pumped in by fans. 

Fungi-growing is a solid fermentation process, not liquid like wine or beer, and the calcium-rich crushed oyster shells buffer the acidity of the carbon dioxide gas. 

“There is a ridiculous amount of science,” said Pacheco, who has bought much of his spawn from a supplier and harvested other spore samples from the gills of native mushrooms, like maitakes he found out foraging.

He cautions anyone thinking of foraging for their own mushrooms to be educated in what is edible and what should be avoided. Of the thousands of varieties that grow in the wild in Connecticut, he knows of only about 15 that may be consumed, he said.

In June, Seacoast will mark its fifth anniversary, but Pacheco said he wasn’t sure after the first year if his farm would survive. When he first started peddling his mushrooms, restaurant chefs and shoppers at farmers markets were not at all inclined to buy.

“I had all these grand ideas, and I had this concept of capturing market share from large commercial growers and thought there is an opportunity here,” he said. “But when I started knocking on doors, I learned that no one really wanted them — no one — not a single restaurant would buy from me.”

It was the same at farmers markets, he said. People were curious but not buying.

“I had made this big investment, and I was losing confidence. It was bad. Really bad,” he recalled.

So Pacheco decided to educate his customers. At the open-air markets, he told passersby about the health benefits of mushrooms, their unique flavor, how much protein they contained, and how to cook them. He handed out recipes and encouraged anyone interested to ask chefs at their favorites eateries to use them. And slowly, his market started growing.

Chef James Wayman at the Oyster Club in Mystic was the first to embrace Seacoast Mushrooms. Pacheco still gets emotional when he talks about the day four years ago when he walked into the restaurant with a box of king oyster mushrooms and Wayman excitedly asked where he had gotten them and grabbed the box and headed off to the kitchen. 

Later the same day, Water Street Café chef and owner Walter Houlihan bought every mushroom Pacheco had on his truck when the mushroom farmer stopped at the restaurant. Ever since, Seacoast has been selling to restaurants across the state, at McQuade’s and Tri-Town supermarkets, and at farmers markets in Westport, New Haven, Stonington and, recently, Greenwich.

At the winter market at the Velvet Mill in Stonington on Saturdays, customers are in line before the 10 a.m. opening, waiting to fill brown kraft bags with mushrooms. Pacheco said customers liken the cost of mushrooms to buying oysters. They sell at the farmers market by the ounce, $1 or $1.50 depending on the type, and there is a steady stream of buyers.

“We owe a tremendous amount of our success to the community,” said Pacheco. “If it were not for the people around here supporting us, supporting our farm, buying our mushrooms, going to restaurants and asking chefs to buy our mushrooms, I would have stopped, I would have baled a long time ago.”

He’s a self-taught mushroom farmer. As a teenager in Little Compton, R.I., he worked on a family apple farm. Later, when he was at Amgen, a relative invited him back to look at other farming ventures for the old family apple orchard. They settled on mushrooms, and Pacheco read everything he could about growing them. He visited Japan multiple times to talk with mushroom growers there, and he experimented.

There’s still a compost pile outside his growing room and, motioning towards it, Pacheco said, “That pile of mushroom compost out there was like 10 times the size it is now. I literally spent my kids’ college education on waste, and that’s when I knew I had to do something different. That’s when I went to Japan.”

He believes he would have perfected his growing formula eventually, but the trips to Japan made it happen quicker.

Five years ago, he decided to venture out on his own and started Seacoast Mushrooms. His growing rooms are thriving, and restaurants and customers are clamoring for his mushrooms now.

He acknowledges eating mushrooms daily, like the maitake, more commonly known as hen-of-the-woods.

“People ask me what to put a maitake in, and I don’t have an answer because it never makes it out of the skillet at my house,” he said. “It literally gets eaten on the stove. If I sauté a maitake in a pan, my 14-year-old daughter will come running.”