About Walla Walla Onion: Known as the "world's best tasting onion", Walla Walla onions have the distinction of being the state of Washington's official state vegetable. This onion's story began in the late 1800s, when a French soldier named Peter Pieri brought sweet onion seed from the island of Corsica to Walla Walla. After careful development, Pieri and his neighbors began growing the big sweet onion called Walla Walla. First harvested in 1900, this onion still enjoys great popularity for its unsurpassed sweetness.
Walla Walla Onion Germination: Since onions take a few months to mature from seed, gardeners with a short growing season may want to start their seed indoors. Plant the seeds 1/2" deep in a flat 2-3 months before the last frost date; keep the soil moist and at room temperature. When the tops begin to flop over, cut them off to 3" to focus the growing on the roots. Four weeks before the last frost or when the soil reaches at least 50 degrees F, transplant the seedlings 6" apart in rows 12" apart. For direct sowing, sow three seeds per inch 1/2" deep in light, rich soil and full sun. Thin the seedlings 2-6" apart, depending on the desired size. Thinned onions can be transplanted or used for fresh eating. For companion planting benefits, plant onions with members of the cabbage family, lettuce, or tomatoes; avoid planting onions with peas or beans. In areas with warmer winters, onions may be grown as a fall or winter crop.
Growing Walla Walla Onion Seeds: Onions need moisture especially in their first several weeks of growth, and they cannot fight against weeds; mulching onions can help with both moisture and weed control. Walla Walla onions are not attractive to deer; they also tolerate cold well.
Harvesting Walla Walla Onion: When the tops of the onions turn yellow or flop over, they have matured and are ready to be harvested. Pull them from the earth, brush off the dirt, and leave them to cure in the sun for a week. If the weather turns rainy, bring them inside to cure in a dry, well ventilated place. When the skin dries, cut the tops down to 1" and trim the roots. Store in a cool, dry place. Walla Walla onions do not store well for long periods of time.
Saving Walla Walla Onion Seeds: Onions need to overwinter before producing seed. In warmer locations, simply apply a thick layer of mulch and remove it in the early spring. In areas with very cold winters, pull up the onions and cut off half the stem; store them at 32-40 degrees F in a dry place until spring, when they can be replanted. Before planting, cut an X in the top of the onion to allow the stalk to emerge. The plants will flower and go to seed. Remove the seed heads when the seeds become visible, taking care not to shatter the heads and lose the seed. Spread the heads out in a dry place with good ventilation, and let them dry for several weeks. Thresh out the seeds and store them in a cool, dry place for up to 2 years.
Detailed Walla Walla Onion Info: Allium cepa. Also known as Walla Walla Sweet. Biennial. 115 days. 7000 seeds per oz. 12-18" height. 4-6" spacing. Produces sweet brown skinned, white onions of a large size. Long day variety.