How A Sleepy Pennsylvania Town Grew Into America's Mushroom Capital

By Dan Charles

Published February 27, 2020 at 4:11 PM EST

Farms in Chester County, Pa., produce 400 million pounds of mushrooms annually. That's about half of all mushrooms grown in the U.S. They're grown indoors in long, gray cinder-block houses built into the side of a hill.

1 of 7 — Farms in Chester County, Pa., produce 400 million pounds of mushrooms annually. That's about half of all mushrooms grown in the U.S. They're grown indoors in long, gray cinder-block houses built into the side of a hill.

Every 10 weeks, the beds inside the mushroom rooms are filled with compost mixed with spores, and covered with peat moss. The spores germinate and create a thick web of white threads called mycelia, shown here. As the fungi try to reproduce, they send up their fruit — the mushrooms.

2 of 7 — Every 10 weeks, the beds inside the mushroom rooms are filled with compost mixed with spores, and covered with peat moss. The spores germinate and create a thick web of white threads called mycelia, shown here. As the fungi try to reproduce, they send up their fruit — the mushrooms.

3 of 7 — Shiitake mushrooms in a growing room at Phillips Mushroom Farms, one of the big mushroom producers in Kennett Square.

4 of 7 — A Mexican worker at Phillips Mushroom Farms. Workers are paid a little more than minimum wage to cut at least 55 pounds of mushrooms an hour.

Southeast Asian workers cut shiitake mushrooms at Phillips Mushroom Farms. The mushroom industry in Chester County, Pa., has relied on several waves of immigrant workers, beginning with Italians in the late 1800s.

5 of 7 — Southeast Asian workers cut shiitake mushrooms at Phillips Mushroom Farms. The mushroom industry in Chester County, Pa., has relied on several waves of immigrant workers, beginning with Italians in the late 1800s.

At an industrial compost facility that supplies the mushroom industry in Kennett Square, ground-up corn cobs are mixed with chicken manure, hay, cocoa shells and horse manure. Over time, growers have learned that mushrooms grow best with this blend of nutrients.

6 of 7 — At an industrial compost facility that supplies the mushroom industry in Kennett Square, ground-up corn cobs are mixed with chicken manure, hay, cocoa shells and horse manure. Over time, growers have learned that mushrooms grow best with this blend of nutrients.

Cocoa shells from a Hershey's chocolate plant in Hershey, Pa., are just one ingredient in the compost that mushroom growers use to feed the fungi.

7 of 7 — Cocoa shells from a Hershey's chocolate plant in Hershey, Pa., are just one ingredient in the compost that mushroom growers use to feed the fungi.