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{{SPlantbox
{{SPlantbox
|familia=Alliaceae
|genus=Allium
|species=cepa
|common_name=Onion
|common_name=Onion
|features=edible
|Temp Metric=°F
|Temp Metric=°F
|jumpin=If this plant info box on watering; zones; height; etc. is mostly empty you can click on the edit tab and fill in the blanks!
|jumpin=If this plant info box on watering; zones; height; etc. is mostly empty you can click on the edit tab and fill in the blanks!
|image=Upload.png
|image=Onions.jpg
|image_width=240
|image_width=240
|image_caption=Onions
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}}
''Allium cepa'' is also known as the "'''garden onion'''" or "[[bulb]]" onion. It is grown underground by the plant as a vertical shoot that is used for food storage, leading to the possibility of confusion with a [[tuber]], which it is not.
{{Inc|
[[Allium]] cepa, Linn. Common Onion. Tall, with large tubular lvs.: scape glaucous, much overtopping the lvs., swollen near middle; fls. white or bluish in a large globular head-like umbel: bulb not making many offsets, distinctly rounded at top and bottom. Var. bulbellifera, Bailey, has bulbels in the place of fls.,—the top, tree or Egyptian onion. Var. multiplicans, Bailey, has dividing bulbs,—the multiplier onion. Persia and adjacent regions.{{SCH}}
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==Cultivation==
{{edit-cult}}<!--- Type cultivation info below this line, then delete this entire line -->
===Propagation===
[[File:2005onion and shallot.PNG|thumb|right|Onion and [[shallot]] output in 2005]]
[[File:Onion whitebackground.jpg|thumb|Onion growing shoots]]
Onions may be grown from seed or, more commonly today, from sets started from seed the previous year. Onion sets are produced by sowing seed very thickly one year, resulting in stunted plants that produce very small bulbs. These bulbs are very easy to set out and grow into mature bulbs the following year, but they have the reputation of producing a less durable bulb than onions grown directly from seed and thinned.
Seed-bearing onions are day-length sensitive; their bulbs begin growing only after the number of daylight hours has surpassed some minimal quantity. Most traditional European onions are what is referred to as "long-day" onions, producing bulbs only after 15+ hours of daylight occur. Southern European and North African varieties are often known as "intermediate day" types, requiring only 12–13 hours of daylight to stimulate bulb formation. Finally, "short-day" onions, which have been developed in more recent times, are planted in mild-winter areas in the fall and form bulbs in the early spring, and require only 9–10 hours of sunlight to stimulate bulb formation.
Either planting method may be used to produce spring onions or [[Scallion|green onion]]s, which are the leaves of immature plants. Green onion is a name also used to refer to another species, ''Allium fistulosum'', the [[Welsh onion]], which is said not to produce dry bulbs.
The [[tree onion]] produces bulbs instead of flowers and seeds, which can be planted directly in the ground.
===Pests and diseases===
{{edit-pests}}<!--- Type pest/disease info below this line, then delete this entire line -->
==Varieties==
*Bulb onion – Grown from seed (or onion sets), bulb onions range from the pungent varieties used for dried soups and onion powder to the mild and hearty [[sweet onion]]s, such as the [[Vidalia onion|Vidalia]] from [[Georgia (U.S. State)|Georgia]] or Walla Walla from [[Washington (U.S. State)|Washington]] that can be sliced and eaten on a sandwich instead of meat.
*Multiplier onions – May refer to perennial green onions, or to onions raised from bulbs that produce multiple shoots, each of which forms a bulb. The second type is often referred to as a [[potato onion]].
*[[Tree onion]] or Egyptian onion - Produce bulblets in the flower head; a [[hybrid (biology)|hybrid]] of ''Allium cepa''s.
*[[Welsh onion]] – Sometimes referred to as green onion or spring onion, although these onions may refer to any green onion stalk.
*[[Leek]]
*[[Yellow onion]] - generally tapered ends, brown skin over the onion, usually sold in 3 lb bags of yellow webbed plastic.
*[[Sweet onion]] - flatter ends and sold individually. Spanish and Vidalia
==Gallery==
<gallery>
Image:Two colors of onions.jpg|Brown and white onions
Image:YellowOnions.jpg|[[Yellow Onions]]
Image:Onion Flower Head.jpg|Flower head of a yellow onion
Image:Muck onions 8640.jpg|Onion fields
</gallery>
==References==
*[[Standard Cyclopedia of Horticulture]], by L. H. Bailey, MacMillan Co., 1963
<!--- xxxxx *Flora: The Gardener's Bible, by Sean Hogan. Global Book Publishing, 2003. ISBN 0881925381 -->
<!--- xxxxx *American Horticultural Society: A-Z Encyclopedia of Garden Plants, by Christopher Brickell, Judith D. Zuk. 1996. ISBN 0789419432 -->
<!--- xxxxx *Sunset National Garden Book. Sunset Books, Inc., 1997. ISBN 0376038608 -->
==Standard Cyclopedia of Horticulture==
{{Inc|
{{Inc|
Onion. All the onions of common or general cultivation are forms of one variable species, Allium Cepa (see Allium, Volume I). It is probably native to south-western Asia, but it has been long domesticated and has varied much. Other cultivated species are A . fistulosum (Fig. 2583), A. Porrum (Fig. 2484), and A. Schoenoprasum (Fig. 2585).
Onion. All the onions of common or general cultivation are forms of one variable species, Allium Cepa (see Allium, Volume I). It is probably native to south-western Asia, but it has been long domesticated and has varied much. Other cultivated species are A . fistulosum (Fig. 2583), A. Porrum (Fig. 2484), and A. Schoenoprasum (Fig. 2585).
Onion fly, or onion maggot, is one of the most severe pests when it enters the field. There seems to be but little encouragement in combating the pest. It often leaves the field as mysteriously as it appeared. This disappearance has been coincident with the application of some supposed remedy, and has consequently led to the recommending of unreliable remedies. A thorough application of ground tobacco stems down the row seems to act as an insecticide and a repellent, besides being of value as a fertilizer. Thrips attack the leaves at times, and become so numerous as to cause the tips to turn brown and finally destroy the whole leaf. Besides the insect injury they open the way for such fungi as Macrosporium. This insect may be treated successfully with kerosene emulsion, tobacco decoction, resin wash and possibly with kerosene-water mixture.
Onion fly, or onion maggot, is one of the most severe pests when it enters the field. There seems to be but little encouragement in combating the pest. It often leaves the field as mysteriously as it appeared. This disappearance has been coincident with the application of some supposed remedy, and has consequently led to the recommending of unreliable remedies. A thorough application of ground tobacco stems down the row seems to act as an insecticide and a repellent, besides being of value as a fertilizer. Thrips attack the leaves at times, and become so numerous as to cause the tips to turn brown and finally destroy the whole leaf. Besides the insect injury they open the way for such fungi as Macrosporium. This insect may be treated successfully with kerosene emulsion, tobacco decoction, resin wash and possibly with kerosene-water mixture.
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==External links==
==External links==
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