- Name: Sweet Walla Walla Onion - Scientific Name: Allium Cepa - Color: Golden Skinned With White Flesh - Plant Seeds: Fall / Outdoors After Frost / Indoors Weeks Before Last Frost - Bloom Time: Spring - Summer - Harvest: 115 Days - Hardiness Zone: Biennial - Plant Height: 12 - 18" - Plant Spacing: 12 - 18" - Light Requirements: Sun - Soil & Water Preferences: Average - Dry - Quantity: 250 Seeds - Other: These Large Sweet Onions Have A Mild Flavor. They Have Been Our Most Popular Onion Variety For Years. Walla Walla Is A Large Onion Measuring Approximately 4" Wide. They Are Great For Salads, Sandwiches, Stir Fries, Or Caramelized. The Walla Walla Onion Is Also An Over-Wintering Variety.