Walla Walla sweet onions are famous for their uniquely mild, sweet flavor. These large, juicy onions were originally grown in Walla Walla, Washington starting in the late 1800s. Today, they are popular home garden vegetables across North America. With care and patience, you can grow sweet Walla Walla onion bulbs from seed.
A Brief History of Walla Walla Onions
The Walla Walla onion traces its origins to the island of Corsica. In the late 1800s, a French soldier named Peter Pieri brought Walla Walla onion seeds with him when he immigrated to the Walla Walla, Washington area. He and other early Walla Walla Valley settlers worked on developing the sweet onion over several generations.
By 1900, the Walla Walla onion emerged as a distinct, large, sweet variety. It quickly became a popular commercial crop in Washington and Oregon. In 2007, the Walla Walla onion became the official state vegetable of Washington.
Key Traits of Walla Walla Onions
Walla Walla onions have several identifying characteristics
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Shape Flattened. globular
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Color: Yellow or white
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Flavor: Very sweet and mild
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Size: Medium to very large bulbs
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Days to maturity: Around 125 days from spring sowing, up to 300 days from fall sowing
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Adaptability: Grows best in zones 3-9
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Storage: Low; use fresh soon after harvest
Growing Walla Walla Onions from Seed
You can purchase Walla Walla onion transplants, but starting from seed allows you to grow a large number of plants. Here are some key tips for success:
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Start seeds indoors: In colder climates, start Walla Walla seeds indoors 6-8 weeks before the last frost. Use individual cells or containers.
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Transplant outdoors: Transplant onion seedlings outdoors 4 weeks before the last frost. Space 4 inches apart in rows 12-18 inches apart.
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Direct sowing: In warmer regions, sow seeds outdoors 1/4-1/2 inch deep in early spring. Thin seedlings to 1.5-4 inches apart.
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Preferred conditions: Grow in full sun and fertile, well-drained soil with a pH of 6.0-7.0.
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Irrigation: Supply at least 1 inch of water per week. Proper irrigation, especially during bulbing, is vital.
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Weed control: Use shallow cultivation and mulching to control weeds. Compete weeds can significantly reduce yields.
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Day length: Walla Walla onions are long-day onions, requiring 13+ hours of sunlight to trigger bulbing.
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Harvest: Harvest when 50% of the tops have fallen over and the necks are soft. Cure bulbs in a warm, dry, shaded area for 1-2 weeks.
Purchasing Walla Walla Onion Seeds
Many seed companies offer Walla Walla onion seeds for sale. When purchasing, look for seeds that are:
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Open-pollinated – Produce plants true to type. Avoid hybrids.
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Untreated – Coating-free for organic growing.
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Fresh – Check seed packets for the year and germination rates.
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Reputable seller – Choose established companies known for quality.
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Organic – Certified organic seed ensures purity.
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Heirloom variety – Traditional strains passed down.
Popular package sizes range from about 250 seeds per packet up to 1 pound bags for large plantings. Prices range from $2 to $15 per packet.
Growing Giant, Sweet Onions Without Fail
Success with Walla Walla onions rests heavily on proper planting times. Long daylight exposure is required to form large bulbs. Follow best planting practices for your climate. Provide rich soil, abundant moisture, and timely harvests. With care, you can enjoy harvests of incredibly sweet onions for months.
Frequency of Entities:
walla walla: 21
onion: 20
seed: 11
sweet: 7
grow: 6
plant: 5
bulb: 4
seeds: 4
large: 3
soil: 3
harvest: 3
rows: 2
irrigation: 2
mature: 2
transplant: 2
indoors: 2
apart: 2
inch: 2
flavor: 1
mild: 1
juicy: 1
globular: 1
yellow: 1
white: 1
zones: 1
spacing: 1
CONTROL: 1
thinning: 1
cultivation: 1
mulching: 1
day length: 1
curing: 1
neck: 1
top: 1
open-pollinated: 1
untreated: 1
coating-free: 1
organic: 1
certification: 1
heirloom: 1
packet: 1
How to Grow Onions Walla Walla’s
FAQ
When to start walla walla onions from seed?
Which onion is sweeter Walla Walla or Vidalia?
How to grow walla walla sweet onions?
What is special about walla walla onions?
Are Walla Walla onion seeds good?
This vegetable seed is a must-have addition to any garden or allotment Sweet, juicy and tear-free! A regional favourite, Walla Walla onion seeds offer sweetness at the first bite with more crunch than tears. It’s mild in taste and less aromatic than any other regular growing onions and provides less sulphur content.
Why is it called Walla Walla sweet onion?
The Walla Walla sweet onion is named for Walla Walla County, Washington, where it is grown. [ 7 ][ 8 ] Its development began around 1900 when Peter Pieri, a French soldier who settled in the area, brought sweet onion seed from the island of Corsica with him to the Walla Walla Valley. [ 9 ]
How do you grow Walla Walla onion seeds?
Can also be sown late December-February 3 seeds per small pot in a propagator or greenhouse at approximately 15-20°C (60-68°F) eventually planting outside in well-prepared soil. Water freely during dry weather. Walla Walla onion seeds are sweet growing onions with less bite and no tears.
Are Walla Walla sweet onions good for long term storage?
Very sweet large bulbs, not for long-term storage. In 2007, the Walla Walla sweet onion was designated as the official vegetable of the state of Washington and was named after the town of Walla Walla, WA. Originally from the island of Corsica, it was brought to Washington by a retired French solider named Peter Pieri.