Allium cepa stands at the center of culinary history in a way few other plants can claim. Historical accounts stretching back more than five thousand years document onions as food, medicine, and even ritual object; the species epithet, cepa, is simply the Latin word for onion, as plainly named as the vegetable itself is indispensable. Origins point toward central Asia and Persia, though the plant has been in cultivation long enough that its wild ancestor is no longer clearly identified. As a cool-season crop, it prefers to go in the ground early, planted half an inch to an inch deep in moist, fertile, well-drained soil as soon as conditions allow in spring.

Harvest timing is one of the more satisfying diagnostics in the edible garden: wait until at least two thirds of the tops have died back, then lift the bulbs gently with a fork to avoid bruising. Curing them for two to three weeks in a dry, airy spot before storage allows the papery skins to fully develop and extends shelf life considerably. Onions are deer and rabbit resistant, tolerant of Black Walnut proximity, and generally low-maintenance if drainage is adequate. Bulb rot in wet soils is the main failure point to guard against.