🧅 Can I Plant Green Onion in Seattle, WA?
Green Onion thrives in cool weather and can be planted now for a fall harvest. Sow seeds soon — they'll be ready around Sep 28–Oct 18, well before the average first frost around Nov 10.
Growing Green Onion in Seattle
Seattle's Zone 8b maritime climate is notoriously cool and cloudy, which means warm-season crops like tomatoes and peppers need all the help they can get. A south-facing wall or greenhouse extension is almost essential for tomatoes. On the plus side, cool-season crops like kale, lettuce, and peas absolutely thrive in Seattle's mild, moist conditions.
In Seattle (last frost around March 18), green onion can go out around February — approximately 4 weeks before the last expected frost, making it an early-season opportunity. Starting seeds indoors 8 weeks before the last frost date gives you a significant head start.
Green Onion thrives between 50°F and 80°F. It tolerates temperatures as low as 35°F, making it a candidate for early spring planting before the last frost date. Expect 60–80 days from transplant to first harvest. Easy and fast. Direct sow in early spring or fall. Harvest young.
Frequently Asked Questions
When can I plant green onion in Seattle, WA?
In Seattle (last frost around March 18), green onion can go out around February — approximately 4 weeks before the last expected frost, making it an early-season opportunity. For best results, start seeds indoors 8 weeks before that — giving you strong transplants ready to go out at the right time.
What is the USDA hardiness zone for Seattle?
Seattle, WA is in USDA Plant Hardiness Zone 8b. The last expected spring frost is around March 18, and the first fall frost arrives around November 15. This zone classification helps you understand which perennials survive winter and when annual vegetables can safely go outdoors.
Is it safe to plant green onion outside in Seattle right now?
That depends on the current weather forecast. Green Onion needs temperatures above 35°F (ideally 50–80°F) to thrive. CanIPlant checks your real 7-day forecast and any active frost alerts to give you a live YES, NO, or WAIT answer — just enter your ZIP code.
Can I grow green onion in Seattle 2026?
Yes — Green Onion grows well in Seattle, WA. With a Zone 8b climate and a growing season of ~242 days, Seattle is well-suited for warm-season crops like green onion. As a frost-tolerant crop, green onion can even go out a few weeks before the last frost date.
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