How to Grow Walla Walla Red Onion
Wikimedia Commons
Walla Walla Red Onion
Allium cepa var. aggregatum
vegetableWalla Walla Red is a large, sweet red onion variety originating from the Walla Walla Valley in Washington state. Known for its mild flavor, thin papery skin, and deep burgundy-red color, it's ideal for fresh eating, grilling, and storage. This long-day onion variety produces large bulbs with a sweet, delicate taste that becomes even sweeter when cooked.
When should you plant Walla Walla Red Onion in your zone?
Get a personalized planting timeline — when to start seeds, transplant, and harvest — based on your USDA zone and local frost dates. Free to start.
Example Walla Walla Red Onion timeline · Pittsburgh, PA (Zone 6b)
-
Plant Walla Walla Red Onion
Around Apr 17Near Pittsburgh's average last spring frost.
-
Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
-
Harvest Walla Walla Red Onion
Around Aug 5≈ 110 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Walla Walla Red Onion dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-9; best suited for cooler to moderate climates
Sign up free to see if Walla Walla Red Onion grows in your zone — and get a personalized planting timeline.
Get my Walla Walla Red Onion timeline →Growth Stages
Seedling
2-3 weeksTiny green shoots emerge from soil; thin, grass-like leaves appear within 7-10 days
Keep soil consistently moist but not waterlogged. Thin seedlings to proper spacing. Provide bright light if growing indoors before transplanting.
Vegetative (Leaf Development)
6-8 weeksPlants develop multiple upright green leaves; above-ground foliage expands significantly; minimal bulb swelling below
Maintain consistent watering and full sun exposure. Apply balanced fertilizer every 3-4 weeks. Remove any flower scapes that form. Keep weeds controlled.
Early Bulb Formation
4-6 weeksVisible swelling begins at soil level; bulbs enlarge as day length increases; foliage remains green and vigorous
Long-day varieties like Walla Walla require 14+ hours of daylight to trigger bulbing. Maintain steady watering. Continue light fertilization with lower nitrogen ratios.
Bulb Maturation
2-3 weeksLarge burgundy bulbs develop thick, papery outer skins; foliage begins to yellow and fall over naturally
Reduce watering as tops brown; once 50% of foliage has fallen over, stop watering to cure bulbs in soil. Do not break over tops manually.
Harvest & Curing
2-3 weeks curingTops completely brown and dried; bulbs can be lifted easily from soil with thin, papery skins
Harvest when soil is dry and tops are fully brown. Cure in well-ventilated area (70-75°F) for 2-3 weeks before storage. Trim roots and dead tops once fully cured.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
-
Use row covers during early growth; apply diatomaceous earth; crop rotation; remove affected plants immediately
-
Spray with neem oil or insecticidal soap; increase humidity; remove infested leaves; use reflective mulch
-
Use disease-resistant varieties; improve drainage; avoid overhead watering; practice crop rotation (3-4 years)
-
Ensure good air circulation; avoid wetting foliage; remove affected leaves; space plants adequately
-
Practice crop rotation; use clean seed sets; improve drainage; sterilize tools
Uses
Fresh eating and salads
CulinaryWalla Walla Reds are prized for their mild, sweet flavor that makes them ideal for eating raw in salads, sandwiches, and salsas. Their tender layers and low pungency distinguish them from storage onion varieties. [source]
Grilling and caramelizing
CulinaryThe natural sugars in Walla Walla onions become even sweeter when grilled, roasted, or caramelized, making them perfect for burgers, steaks, and side dishes. Their sweetness develops beautifully when cooked slowly over low heat. [source]
Natural dye and traditional medicine
HouseholdThe deep red skins contain anthocyanins and quercetin compounds traditionally used in herbal remedies for circulation and inflammation. Red onion skins can also be used to create natural fabric dyes. [source]
Anti-inflammatory benefits
MedicinalRed onions contain high levels of antioxidants and sulfur compounds that have been studied for their potential anti-inflammatory and cardiovascular health properties. Regular consumption may support immune function and heart health. [source]
Pollinator garden benefit
WildlifeIf allowed to flower, Walla Walla onions produce attractive spherical clusters of pink-purple flowers that attract bees and beneficial insects. Leaving some bulbs unharvested to bolt provides late-season nectar. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Harvest when 50% of foliage has naturally fallen over and soil is dry. Gently lift bulbs from soil with a garden fork. Cure in a warm, well-ventilated area (70-75°F) for 2-3 weeks before trimming roots and tops. Do not wash bulbs before storage. Store in cool (50-55°F), dry conditions with good air circulation; properly cured Walla Walla Reds store for 3-4 months.
Fun Facts
- 🌱 Walla Walla Reds were developed in the 1930s in Walla Walla, Washington, and are so synonymous with the region that they received a geographical indication (GI) status, meaning only onions grown in the Walla Walla Valley can legally be labeled 'Walla Walla Onions.'
- 🌱 These onions are classified as 'long-day' varieties, meaning they require 14+ hours of daylight to trigger bulb formation—which is why they thrive in northern climates and perform poorly in southern regions where day length is shorter.
- 🌱 Walla Walla Reds have a naturally lower sulfur content than most storage onions, which is why they taste sweeter and milder; the sulfur compounds that create the typical 'onion bite' and tear-inducing effect are much reduced in this variety.
Join 30,000 gardeners planning their gardens with LizPlants.
Get your personalized Walla Walla Red Onion planting timeline
Tell us your zip code and we'll calculate exactly when to start Walla Walla Red Onion seeds, transplant seedlings, and harvest — based on your USDA zone and local frost dates. Includes calendar reminders and printable task lists. Free to start.
Get my Walla Walla Red Onion timeline →