The Walla Walla Sweet onion is grown in Walla Walla County, but finds its origins on the island of Corsica. Over a century ago, a retired French soldier named Peter Pieri found a sweet onion seed there and brought it to the Walla Walla Valley. The sweet onion had impressive winter hardiness well-suited for the climate of southeastern Washington. Soon Pieri and many Italian immigrants in the area began harvesting the seed. Over several generations of careful hand selection, the sweet onion developed greater sweetness, size, and shape.
Today, there are approximately 18 growers producing Walla Walla Sweet onions on 400 acres of farmland in the Walla Walla Valley. Approximately 32,500 pounds of Walla Walla onions are harvested per acre each year. Walla Walla onions are one of the only non-hybrid sweet onions that are members of the Amaryllidaceae family. These onions are only allowed to be labeled as Walla Walla if they meet specific quality regulations, and are grown in the designated region. Sweet onion season is mid-June through August, and, since 1984, Walla Walla has celebrated the Sweet Onion Festival every July.
July 10th of each year will be recognized as Walla Walla Sweet Onion Day.