The Walla Walla Sweet Onion story began nearly a century ago on the Island of Corsica, off the west coast of Italy. It was there that a French soldier, Peter Pieri, found a sweet onion seed and brought it to Walla Walla in the late 1800’s. At the time, Italian immigrant gardeners comprised the core of Walla Walla’s gardening industry, and several were Pieri’s neighbors. Impressed by the new onion’s winter hardiness, they and Pieri harvested the seed.
This “French” onion developed over several generations through the process of carefully hand selecting onions from each year’s crop, ensuring exceptional sweetness, jumbo size, and round shape. Today’s growers realize they’re not just raising sweet onions, but cultivating a tradition.
Although one plant per module is effective, growing three to four plants per module saves space. Sow five to six seeds per module and thin out if necessary, to three or four plants. When multi-seeded modules are planted out, the onions form a clump of bulbs.
Once the soil is drier and beginning to warm up, start sowing directly.
Sow onion seeds from late winter until mid-spring 1.3cm (½in) deep in rows 20cm (8in) apart. Thin out first to 5cm (2in) and later to 10cm (4in). Closer planting will result in more bulbs and a heavier crop, but smaller bulbs.
Sow shallots a little bit later from early- to mid-spring. Unlike shallot sets, seed-grown plants will only produce a single bulb. Thin out as required to 2.5-7.5cm (1-3in) apart.