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A freshly pulled Walla Walla onion showing its large sweet yellow bulb and roots

How to Grow Walla Walla Onions From Seed

By Maxim Kaufman — Founder & CEO, Organo Republic

Updated July 2026

Walla Walla is the famously sweet, mild yellow onion from the Pacific Northwest, prized for its very large bulbs and gentle flavor you can almost eat like an apple. It is a short-day type, so it sizes up best in the South or when overwintered, and it is meant to be eaten fresh rather than stored. Here is what makes this variety special and how to get the best from it.

This is the quick guide to Walla Walla. For the full step-by-step on starting seeds, sowing, feeding, and troubleshooting onions, see our complete guide to growing onions from seed.

Quick start

Start seeds indoors about 8 to 10 weeks before your last frost, or sow in fall in mild-winter regions for the biggest bulbs. Transplant seedlings 4 to 6 inches apart in full sun and rich, well-drained soil. Keep them evenly watered and fed until the bulbs swell, then ease off. Expect about 110 to 125 days to harvest, when the tops flop and yellow.

Best tip

Walla Walla is a short-day onion, so it bulbs best in the South or when overwintered in milder zones; long-season northern gardeners can still grow it from an early indoor start but should not expect it to store. In cold-winter areas start seeds indoors early and keep growth steady, since a hard cold snap on young plants can trigger bolting.

At a glance

Botanical nameAllium cepa

Plant typeShort-day sweet onion

USDA zones3 to 9 (grown as an annual)

SunFull sun (6 or more hours)

Days to maturity110 to 125 days

Height12 to 18 inches

Spacing4 to 6 inches apart

WaterSteady and even; about 1 inch a week

Uses

Walla Walla is the classic sweet, fresh-eating onion. Slice it raw onto burgers, sandwiches, and salads where its mild flavor shines, or grill thick rings until they caramelize. It is too sweet and moist to store well, so enjoy it fresh through summer rather than curing it for the pantry.

Frequently asked questions

How long do Walla Walla onions take to grow?

From transplant, Walla Walla needs about 110 to 125 days, plus 8 to 10 weeks of indoor growing first. Fall-sown, overwintered plants in mild climates mature in early summer.

Are Walla Walla onions sweet or storage onions?

They are sweet, fresh-eating onions with high moisture and low pungency, which makes them delicious raw but poor keepers. Eat them within a few weeks rather than curing them for long storage.

Can I grow Walla Walla onions in the North?

Yes, but as a short-day type they bulb best in the South or when overwintered. Northern gardeners can grow them from an early indoor start for summer eating, though the bulbs may be smaller.

How big do Walla Walla onions get?

Well-grown Walla Walla bulbs are large, often reaching the size of a softball, with a flattened globe shape and thin, straw-colored skin.

How do you cure and store Walla Walla onions?

Walla Walla is a sweet onion, so it keeps only a few weeks, not months. Once the tops flop over, lift the bulbs and cure them somewhere warm, dry, and airy for one to two weeks until the necks are papery, then store cool and dry.

Ready to grow your own? Our 8 Onion Variety Pack lets you grow Walla Walla alongside seven other onions from a single order. For the full step-by-step, see our complete onion growing guide linked at the top of this page.

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Want more onions? These value packs pair sweet onions like Walla Walla with other varieties:

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Onion Seeds Variety Pack – Non-GMO Heirloom8 onion varietiesEight sweet, storage, and specialty onions in one pack — the easiest way to grow a whole spread of varieties from a single order.

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By Maxim Kaufman — Founder & CEO, Organo Republic

Maxim founded Organo Republic in 2017 and personally selects, tests, and grows the heirloom, non-GMO varieties the company offers. Under his leadership, Organo Republic was named Agri Business Review’s Top Non-GMO Seed Variety Solution 2026.