Walla Walla Onion
Allium cepa
Seeds per pack ~125
Germination: 89% Sep 2025 Packed for 2026
Origins, Migration, and History of Domestication: The Walla Walla Onion traces its lineage to sweet onion varieties brought to the Pacific Northwest by French soldiers and settlers in the late 19th century. These early introductions were likely derived from European sweet onions, themselves part of the long domestication history of Allium cepa, which began in Central Asia and spread through the Near East into Europe over thousands of years. Developed in Walla Walla, Washington, and is the official state vegetable of Washington. In the Walla Walla Valley, farmers selected for mildness, large bulb size, and overwintering ability, gradually stabilizing the variety into what became known as the Walla Walla Sweet Onion. By the early 20th century, it had become a regional heirloom, closely tied to local soil conditions and seasonal cycles, and today it is protected under geographic indication laws that preserve its cultural and agricultural identity.
Appearance and Characteristics: Walla Walla Onions are known for their large, globe to slightly flattened bulbs with thin, papery, light golden to straw-colored skins. The interior flesh is crisp, white, and notably juicy, with a high water content and low sulfur compounds, which give the onion its signature sweetness and mild flavor. Compared to storage onions, they have a shorter shelf life but superior fresh-eating quality. Plants produce tall, hollow green leaves typical of bulb onions and can grow quite vigorously when established in fertile soils.
Culinary Uses: Renowned for their sweetness, Walla Walla Onions are ideal for fresh applications where their mild flavor can shine. They are excellent sliced raw in salads, layered into sandwiches, or used in salsas. Their natural sugars also make them exceptional for caramelizing, grilling, or roasting, where they develop a rich, mellow depth. In regional cuisine, they are often featured in onion rings, soups, and savory tarts, emphasizing their tender texture and low pungency.
Growing Tips and Sow Depth: Walla Walla Onions are typically grown as an overwintering crop in regions with mild winters (USDA Zones 5–9). Seeds are best sown in late summer to early fall (August–September), allowing plants to establish before winter dormancy. Sow seeds at a depth of about ¼ to ½ inch in well-drained, fertile soil rich in organic matter, with a pH between 6.0 and 7.0. Space plants 4–6 inches apart in rows 12–18 inches apart. Consistent moisture and full sun are critical for proper bulb development. Walla Walla are long-day onions, meaning it requires long daylight hours (14–16 hours) to initiate bulb formation. Because they are long-day onions, they require increasing daylight in spring to trigger bulbing.
Harvesting Guidance: Harvest Walla Walla Onions in late spring to early summer (typically June–July) when the tops begin to yellow and fall over naturally. Gently lift bulbs from the soil and allow them to cure in a dry, shaded, well-ventilated area for several days to a week. Due to their high moisture content and thin skins, they do not store as long as other onions and are best used within a few weeks to a couple of months. For extended use, they can be refrigerated or processed shortly after harvest.
