Walla Walla Sweet Heirloom Onion Seeds

Walla Walla Sweet Onion is famous for its enormous, mild bulbs and unusually sweet flavor, a garden treasure for fresh slicing, grilling, and summer cooking. The pale golden onions mature into impressive round bulbs with crisp white flesh and far less bite than ordinary storage onions. This open-pollinated, non-GMO heirloom is a standout choice for gardeners who want an onion worth showing off.

History

Walla Walla Sweet Onion was developed in the Walla Walla Valley of Washington, where the region's fertile soil, cool nights, and long summer days helped shape its reputation. The variety is connected to Corsican onion seed brought to the valley in the late 1800s and refined through generations of local growing. Its mild, sweet flavor became so distinctive that Walla Walla onions earned a protected regional identity and a loyal following far beyond the Pacific Northwest.

Plant Profile

• Days to Maturity: 90–120 days, depending on growing method
• Bulb Size: Large rounded bulbs, commonly 3–4 inches across
• Plant Size: 18–24 inch upright blue-green leaves
• Plant Type: Long-day annual bulb onion

Flavor Profile

Walla Walla Sweet Onions are crisp, juicy, and naturally mild with a gentle sweetness that makes them especially good raw. Their clean white flesh softens beautifully when grilled, roasted, or caramelized without becoming aggressively sharp.

When to Plant

Start seeds indoors 10–12 weeks before your last expected frost, or direct sow as soon as the soil can be worked in spring. Transplant seedlings when they are about pencil-thick and give bulbs a long, sunny season to size up. Walla Walla is a long-day onion, so it performs best where summer days provide plenty of daylight. Check your USDA Plant Hardiness Zone Map for local timing.

Growing Tips & Planting Dimensions

Sow seeds 1/4 inch deep in fine, well-drained mix and transplant or thin seedlings 4–6 inches apart for large bulbs. Grow in full sun with loose, fertile soil and steady moisture. Keep weeds down because onions compete poorly, and stop watering as the tops begin to fall and bulbs approach maturity.

• Water at soil level to keep leaves dry and reduce disease pressure.
• Rotate alliums to a new bed when possible to support healthy soil.
• Mulch lightly after the soil warms, keeping mulch away from the bulb necks.

🌱 Gentle Cover Germination 🌱

Into the surface — thin cover only, no light needed

Walla Walla Onion seeds are small, but they grow into strong plants when given steady moisture and a little patience. A fine mix and a light cover help these slow-starting seedlings emerge evenly.

How to Germinate Successfully:

1. Start with the right foundation. Use a fine seed-starting mix — not garden soil or coarse potting mix. Sift it if needed. Small seeds need a smooth, even surface to make good contact and germinate reliably.
2. Cover lightly — just barely. Press seeds onto the moist surface and cover with no more than 1/8 inch of finely sifted mix. These seeds do not need light to germinate but they do not want to be buried either.
3. Mist, do not drench. Use a spray bottle to keep the surface evenly moist. Watering from above can wash small seeds away before they ever get started.
4. Warmth is your friend. These seeds germinate best at 65–75°F. A heat mat can help if your growing space runs cool.
5. Trap the humidity. Cover your tray with a humidity dome or a loose piece of plastic wrap. This keeps moisture and warmth stable while you wait.
6. Give them time. Keep conditions consistent and expect sprouts in about 7–14 days. Onion seedlings are fine and slow-growing at first, so do not give up early.
7. Thin with scissors, not fingers. Once seedlings appear, snip extras at the soil line rather than pulling. This protects the roots of the seedlings you are keeping.

Growth Type & Harvest Yields

Walla Walla forms a single large bulb below the soil with upright leaves above ground. Given full sun, rich loose soil, and a long growing season, each plant can produce one impressive onion. The bulbs are best enjoyed fresh because their high moisture content makes them less suited to very long storage.

Knowing When to Harvest

• Harvest green onions early, or wait until bulbs have rounded up and the tops begin to soften and fall.
• Look for firm bulbs with papery pale-golden skin and a narrowing neck.
• Lift bulbs gently with a garden fork rather than pulling hard on the leaves.
• Let freshly harvested onions cure in a warm, dry, airy place for a short period before storing.
• Store Walla Walla onions in a cool, dry, well-ventilated spot and use them ahead of hard storage varieties.

Companion Plants & Mutual Benefits

• Carrots — onions and carrots make efficient use of the same bed and may help confuse each other's pests.
• Lettuce — fills space between young onions while bulbs are still developing below ground.
• Beets — share the cool-to-mild growing season and use a different root shape.
• Chamomile — attracts beneficial insects near the allium bed.
• Summer Savory — is a traditional garden pairing that makes good use of sunny bed edges.

How to Enjoy

• Slice raw into sandwiches, burgers, salads, and salsa.
• Grill thick rounds until caramelized at the edges.
• Roast whole or halved bulbs alongside summer vegetables.
• Make sweet onion relish, pickles, or a fresh onion jam.
• Use the green tops like mild scallions while bulbs are developing.

Order Today

Grow the famous sweetness of Walla Walla in your own garden with Walla Walla Sweet Heirloom Onion Seeds. Give these bulbs sun, room, and time, then enjoy a harvest made for fresh summer meals.