Peter Pieri, a French soldier brought a sweet Italian onion from the island of Corsica in the Mediterranean, to the Walla Walla valley in southeastern Washington and continued growing and developing it into the famous sweet onion that it is today. Walla Walla onions are sought after for their sweet, crisp, juicy white flesh. The low amounts of pyruvic acid in these onions allow for it to be less sharp and unpleasant, and the high amount of sugar and water in them makes them absolutely wonderful when cooked. These are a long day onion meant for growing in Northern latitudes where the sun shines for 14+ hours per day.
Sow seeds 1/4″ deep indoors 6-8 weeks before last frost. Germination occurs around 15-20 degrees Celsius, so do not use a heat mat for germination. Transplant outdoors 8″ apart in good organic compost amended soil, in full sun when all chance of frost has past. When 50% of the onion tops fall over, push the rest down and harvest within a week. Cure in the sun for 10 days in the field and cover if rain occurs during those 10 days. Curing onions is crucial for storage.