It truly is a local favorite. The original seed came from the French island of Corsica southwest of Italy. It was brought to Walla Walla in the late 1800's by a retired French soldier. It quickly became popular with immigrant Italian farmers who for generation after generation selectively bred the onion for superb sweetness. Today, only about 60 growers cultivate the official Walla Walla Sweet onion.
Sulfur contributes to an onion's shelf life.
Low in sulfur, the Walla Walla Sweet will only keep for a few weeks after harvest. Despite the regulations controlling commercial growers, the home gardener is free to grow Walla Walla Sweets anywhere. Seed and plants are available from many local and mail-order sources. Plants are locally available in late Winter. There is no question that the quality of the onions grown in the Walla Walla Valley is exceptional.