Onion (Walla Walla)

📖 About This Plant

Onion (Walla Walla Sweet) is the most celebrated sweet onion grown in the continental United States — an Italian transplant developed in the Walla Walla Valley of Washington State from seeds brought by a Corsican soldier in the 1900s and refined by generations of local farmers into a genuinely distinct variety. Walla Walla Sweets are exceptionally mild and juicy with a high water content and a sweet flavor so pronounced that they can be eaten raw in thick slices like a tomato — an experience unavailable with any pungent storage onion. The bulbs grow large (often baseball-sized or bigger) with flat, slightly squat proportions and thin, pale gold papery skin. They do not store well (2–4 months maximum compared to 8–12 months for pungent storage types) because their high water content and low sulfur compounds — the same traits that make them sweet — reduce shelf life.

📊 Quick Facts

📅 When to Plant in Your Area

🌱 Care Tips

Walla Walla Sweet onions are long-day varieties, requiring 14+ hours of daylight to form bulbs — they are suited to US zones 3–8 (above the 35th parallel roughly) and should not be grown in the Deep South where short-day Vidalia-type onions perform better. Sow seeds indoors in January–February (12–14 weeks before last frost), or purchase transplants in spring. Transplant outdoors 4–6 weeks before last frost when seedlings are pencil-thick. Space plants 4–5 inches apart — Walla Walla Sweets need room to develop their characteristically large bulbs and will be stunted by crowding. Grow in full sun with loose, well-drained, fertile soil. Feed with nitrogen-heavy fertilizer every 3–4 weeks until mid-June, then stop completely — late-season nitrogen prevents proper bulb curing and reduces storage life. Stop watering when the necks of the plants start to soften and tops begin flopping over (typically late July). Harvest when 50–75% of the tops have fallen over; do not wait for all tops to fall or the outer wrapper leaves may decompose. Cure in a warm, well-ventilated area out of direct sun for 3–4 weeks. Walla Walla Sweets will keep 2–4 months refrigerated — their short storage life makes them a fresh-eating onion, not a storage one. Eat them raw in salads, on burgers, or in French onion soup within weeks of harvest for peak quality.

🤝 Companion Plants

These plants grow well alongside Onion:

🌿 Related Vegetable

More vegetable that grow in similar conditions:

❓ Frequently Asked Questions