Walla Walla

Onion

Zone 9b Save Garden

🌱 90d to harvest Bulbing

Sweet, honeyed fragrance rises as soon as you lift the bulb—Walla Walla’s mild, juicy sweetness is the hallmark that makes it a f…

Crop Dates

Milestone	Date
Start Indoors	Direct Sow
Last Frost	Feb 9th
Transplant / Sow Outdoors	Feb 9th
Harvest Begins	May 10th
Harvest Ends	Dec 9th

Crop Details

Trait	Value
Days to Maturity	90
Sun Requirements	Full Sun
Growth Habit	Bulbing
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	70
Min Soil Temp (°F)	50
Min Night Temp (°F)	28
Harden Off (days)	7

Recommended Companions

Frequently Asked Questions

What’s a common disease or pest problem for Allium cepa (Walla Walla onion) and how do I fix it?

Watch for onion thrips and purple blotch (Alternaria porri), which show up as silvery streaking or purplish spots on leaves and can quickly weaken bulbs. Spray with insecticidal soap for thrips early in the day, and remove badly spotted leaves; improve airflow and avoid wetting foliage when watering. If purple blotch is active, use a labeled fungicide that targets Alternaria on onions and rotate beds so you don’t plant Allium crops in the same soil year after year.

How often should I water Walla Walla onions during the main growing phase?

During active bulbing growth, keep soil evenly moist but not waterlogged—aim for about 1 inch (2.5 cm) of water per week, split into 2–3 waterings during hot spells. When the bulbs begin to enlarge (after tops establish), water deeply only when the top 1–2 inches of soil feel dry, then let excess drain. Stop regular watering once most tops start to flop, so skins can dry and bulbs store better.

How can I tell when Walla Walla (Allium cepa) is ready to harvest?

Harvest when about 50–70% of the plants have fallen over and the necks are starting to dry; at that point the bulbs have usually reached full size (around 90 days from sowing/planting, depending on start type). Lift a few bulbs to check—skins should feel papery and tight, with minimal soft spots. After lifting, cure onions in a warm, airy place out of direct sun until necks are fully dry.

Sweet, honeyed fragrance rises as soon as you lift the bulb—Walla Walla’s mild, juicy sweetness is the hallmark that makes it a favorite for fresh use. At maturity, the bulbs form broad, paper-sheathed globes with a clean, crisp bite and a tender, succulent texture that shines in simple preparations. Grow Walla Walla for its dependable 90-day timing and its bright, sweet character that turns everyday salads and fresh toppings into something special.

Sowing Tips

Transplant Conditions

Wait until soil reaches 50°F and nights stay above 28°F before moving outdoors. Harden off for 7 days first.

Expert Note

For Walla Walla (sweet, fresh-eating onion), prioritize consistent moisture and a sunny site, then harvest promptly since storage life is short.