Sibul

Sibul is the Estonian term for the edible bulb of the plant Allium cepa, commonly known as the onion in English. It is cultivated as an annual for its bulb, and sometimes for young greens. The onion belongs to the Amaryllidaceae family and grows as a herbaceous plant with hollow leaves and a short flowering stalk.

The bulb consists of concentric layers of fleshy scales, enclosed in a dry, papery skin that can be white, yellow, or red. Flavors range from mild and sweet to sharp and pungent, influenced by variety, growing conditions, and age. Onions store well when cured and kept in a cool, ventilated area.

Common cultivated types include yellow, white, and red onions; sweet onions such as Vidalia or Walla Walla are selected for lower sulfur content and milder taste. Onion varieties are categorized by photoperiod sensitivity: short-day onions bulb under shorter day lengths, long-day onions under longer day lengths, affecting where they are best grown. Related forms include shallots and green onions (scallions).

Cultivation requires well-drained, fertile soil, full sun, and steady moisture during bulb formation. Seeded or sets are planted in spring or autumn depending on climate. Bulbs are typically harvested when the tops fall over or cease growth; they are cured to dry the skins before storage.

In cooking, onions are used as a base for broths, sautés, and sauces, or eaten raw in salads. They provide vitamin C, B vitamins, fiber, and bioactive sulfur compounds. Storage should be cool and dry; avoid moisture and warmth to prevent sprouting and spoilage. Onions may cause odor in breath and can trigger allergies in sensitive individuals.