The Field Guideby Moss & MarrowThe Field Guideby Moss & Marrow
Also called uien, sjalot, sjalotten.
In the Netherlands, onions are in season July to October, at their best in August and September. After the harvest, Dutch stores carry them until June. In November, Dutch onions come from store or from under glass, not from the field.
Onions are lifted from July to October and dried, then sold from store for the rest of the year. The Netherlands is one of the world's largest onion exporters.
Dry, papery skin and a hard neck.
Quercetin, a flavonoid concentrated in the outer layers, plus fibre, vitamin C and the sulphur compounds that make you cry.
To get the most: Quercetin sits in the outer rings, so peel thinly. It survives cooking; the vitamin C does not.
On our nutrient density chart, a normal serving of onion (80 g) gives about a tenth of a day's vitamin C, counting what your body absorbs.
Content per NEVO, the Dutch food composition database. This describes what the food contains, not what it does for you.
Store in a dark, airy place, not the fridge. Caramelise a big batch slowly and freeze in portions.
Skins and ends go in the stock bag; they give colour. Sprouting onions can be planted for green tops.
21 producers in The Field Guide sell onions, according to their own website or shop list, each checked against our inclusion criteria and listed by province. Another 165 growers passed our bar for this food group; we have not yet recorded what each of them grows, so ask them or search the map.
Open on the map →Dates read on 2026-10-11. If a window on this page is wrong, tell us with a source.
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A free list of what’s in season this month, then one slow email a month with seasonal tips and goodies.