Walla Walla Onion

Sow Walla Walla onion seedlings in early spring for a late June harvest

Walla Walla onions are one of the treasures of my summer garden. They are among the earliest to be transplanted out in spring and one of the first to be harvested, usually by late June. These exceptionally sweet onions add flavour to fresh salads, sandwiches and stir-fries.

Walla Walla onions were introduced to western North America over 100 years ago by a French soldier, Peter Pieri, who brought seed over from the Italian island of Corsica. Since then onions with exceptional sweetness, jumbo size and round shape have been selected and propagated by growers.

How to grow Walla Walla onions

An easy way to establish an onion bed is to buy onion sets that are sold bare root, in bundles of about 60, and transplant the finger-size seedlings into the garden in early spring.

Growing from seed is another alternative, especially since spring transplants can be in limited supply, but the trick is to plan ahead.

Early in the summer, before seeds are returned to vendors or sold out, head down to the garden centre and purchase Walla Walla seeds; if you leave it too late you may not find them. Come September, sow the seeds according to package directions, using a sterilized seed-starting soil. Then place your flats in a cold frame or greenhouse (they can take up to -20ºC/-4ºF). Gently mist and foliar feed, using an organic 4*2*3 as needed. Be careful not to overwater, and do keep in mind that wet soil is cooler than dry soil.

Over the fall and winter your onions will slowly germinate and grow; come late March they will be large enough to plant out. Spacing is easy: just visualize a mature onion and leave that much space. The rows need not be more than 15 cm (6 in.) apart.

In milder areas, such as on the coast, you can direct-sow the seed into the garden bed. Sow by September 1 to ensure the soil is warm enough for germination. Over winter mulch lightly with fallen maple leaves. In early spring the onions will be off to a great start and will be poking through the leaves. After the last frost, remove the leaves so the sun can warm the soil.

If you have never grown Walla Wallas you’ll enjoy them, but remember they don’t keep, so grow only what you and your friends will enjoy fresh.