As the last Wisconsin glacier retreated at the end of the Ice Age, it left behind mineral deposits that enriched the Midwestern state's soil and made the land perfect for ginseng, which can grow in the same plot of earth only once.

For generations, farmers in Wisconsin's Marathon County cultivated ginseng in the land's dark, fertile soil that gives it its strong bittersweet flavour, aided by winters cold enough to freeze the root in the ground and summers mild enough to stave off diseases caused by heat and humidity.