The Persian nuts later became known as English walnuts, a nod to the British sailors who carried them all over the world on their ships. In America, the English walnuts are better known than the native black walnuts, probably because their shells are more easily cracked. The walnut has long been revered in the Perigord region of southwest France, now known as the Department of the Dordogne. There, the locals routinely blend them into savory soups and sauces, breads and cookies. The United States is the largest walnut producer in the world.
Domestic production is highest in California, especially in the Central Valley.
Here in Sonoma County, Luther Burbank was among the first to conduct walnut-breeding experiments. Although walnut orchards in Sonoma County are now few and far between, the walnut industry still yields a healthy profit in Lake County, where many growers are making the transition to organic. If you don't have tons per acre, you try to look for another advantage. Recently, however, wine grapes have begun to encroach on the Lake County hillsides where walnut trees were once planted in abundance. In Lake County, the harvest takes place from the last of October through November.