Allium cepa 'Walla Walla'
vegetableA large, famously sweet and mild onion from Washington State. Walla Walla onions are some of the largest and juiciest of all sweet onions, with such low pungency they can be eaten like an apple by some people. They do not store well because of their high water content, so they are best enjoyed fresh over a short season.
Sun
full sun
Water
Every 3 days
Harvest
~110 days
Difficulty
easy
Lifecycle
biennial
Leaves year 1, flowers year 2
Spacing
4-6 in
Planting Depth
1/2-1 in (sets or transplants)
Soil pH
6.0-7.0
Soil Type
Loose, well-draining
Hardiness Zones
Zones 3 – 10
Grown as an annual. This range is its winter hardiness, but you can grow it for a single season in any zone.
When to Fertilize
Nitrogen-rich fertilizer at planting; balanced side-dress when tops reach 6 inches
Fertilizer
High-nitrogen early; taper off once bulbs begin to swell
Walla Walla Sweet onions are long-day types suited to northern gardens. Plant transplants or sets 4 to 6 weeks before last frost. They prefer heavier soil than most onions. Keep beds weed-free. For the largest bulbs, plant slightly deeper and hill up soil as bulbs develop. Stop watering completely once tops begin to fall. Plan to use shortly after harvest. These do not keep.
Start seeds indoors
Feb 4
Transplant outdoors
Mar 18
Projected first harvest
Jul 6
Good neighbors that attract beneficial insects or deter pests
Proactive ways to stop trouble before it starts. Tap a name with an arrow for its full guide
Row cover from planting; crop rotation annually; avoid fresh manure
Reflective silver mulch; spinosad spray if severe
Well-draining soil; avoid wet conditions; copper fungicide if needed
Plant in well-draining soil; strict rotation; avoid injury to bulbs when harvesting
Harvest when tops fall naturally. Walla Walla onions are ready earlier than storage types. Cure for just 1 to 2 weeks. They do not need the extended curing of storage onions. Use within 2 to 4 weeks of harvest. Refrigerate for up to 1 month maximum. Excellent sliced thick on burgers or in French onion soup.
Good source of vitamin C, B6, quercetin, and potassium. Lower sulfur content than yellow storage onions contributes to extreme mildness and shorter storage life. High water content means more water-soluble vitamins per serving when eaten raw.
For educational and informational purposes only. HomeSown is not medical, health, or other professional advice. Always positively identify any plant before handling or eating it; some plants, and some parts of otherwise-edible plants, are toxic. Consult a qualified professional before consuming or otherwise using any plant, especially if you are pregnant, nursing, taking medication, or have a health condition.