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ALLIUM cepa

Image of Allium cepa

Felder Rushing

Family

Liliaceae

Botanical Name

ALLIUM cepa

Plant Common Name

Garden Onion

General Description

Fresh grown onions just taste better. These popular vegetables come in many shapes and colors and are quite easy to grow if you have good, friable soil and lots of sun.

The onion is a perennial that’s grown as an annual root vegetable. Unknown in the wild, Allium cepa may descend from several species found across Central Asian to include Allium oschaninii, Allium praemixtum, Allium vavilovii, Allium pskemense, and Allium galanthum. It has a long cultivation history and is intrinsic to many culinary cultures.

The onion plant produces a dense upright cluster of hollow pale green leaves that rise from a bulb that grows larger and more bulbous as the season progresses. White or lavender-pink balls of star-like flowers emerge from plants in the spring of the second year, though these are rarely seen because plants are generally harvested after the first year. Some varieties also produce stems topped with clusters of small bulblets (bulbils) at their tops.

Onions may be round, flattened or torpedo-shaped and red, yellow, or white. They are true bulbs with distinctive rings and are surrounded by a papery outer covering. Some onions are pungent while others like ‘Walla Walla’ are known for their impressive sweetness. Those with a higher sugar content don’t store well whereas more pungent varieties keep better.

Garden onions are categorized by the day length needed for them to form large bulbs. Short-day varieties, which require 10 to 12 hours of daylight, are typically planted in fall to early winter, and produce bulbs in the spring. Short-day onions are usually sweet, but do not store well. They include ‘Bermuda’, ‘Grano’, and ‘Supersweet'. Intermediate-day onions such as ‘Red Torpedo’ and ‘Ringmaker’ require 12 to 14 hours of daylight, and are planted in the early spring and harvested in the fall. They store moderately well. Long-day onions need 14 to 16 hours of daylight to form bulbs and are best suited to subarctic regions. The extremely long days there result in pungent onions that store well.

It is necessary to provide these veggies with even moisture as well as full sun and rich soil. Onions can be seed grown but most are planted using sets, or small bulbs. Sets should be planted with their tops extending just above the surface of the soil. Harvest your onions when their leaves start to show decline. Good keepers should be stored in a dry, cool, well-ventilated area.

Onions are fun to plant and great for kids, Try braiding their dry tops to make an attractive hanging onion cluster for fall.

Characteristics

  • Sunset Zone

    A1, A2, A3, H1, H2, 1a, 1b, 2a, 2b, 3a, 3b, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

  • Plant Type

    Vegetable

  • Sun Exposure

    Full Sun, Partial Sun

  • Height

    2'-3' / 0.6m - 0.9m

  • Width

    4"-12" / 10.2cm - 30.5cm

  • Bloom Time

    Late Spring, Early Summer

  • Native To

    World/Pandemic, North America, Europe, Russia/Siberia, Northern Africa, Asia, India

Growing Conditions

  • Soil pH

    Neutral

  • Soil Drainage

    Well Drained

  • Soil type

    Loam, Sand

  • Growth Rate

    Fast

  • Water Requirements

    Average Water

  • Habit

    Upright/Erect

Ornamental Features

  • Flower Interest

    Showy

  • Flower Color

    White, Yellow Green

  • Foliage Color (Spring)

    Green, Gray Green

  • Foliage Color (Summer)

    Green, Gray Green

  • Foliage Color (Fall)

    Green, Gray Green, Yellow Green

  • Fragrant Flowers

    Yes

  • Fragrant Fruit

    No

  • Fragrant Foliage

    Yes

  • Bark or Stem Fragrant

    Yes

  • Flower Petal Number

    Single

  • Repeat Bloomer

    No

  • Showy Fruit

    No

  • Edible Fruit

    No

  • Showy Foliage

    No

  • Foliage Texture

    Medium

  • Foliage Sheen

    Matte

  • Evergreen

    No

  • Showy Bark

    No

Special Characteristics

  • Usage

    Edible, Herb / Vegetable

  • Sharp or Has Thorns

    No

  • Invasive

    No

  • Self-Sowing

    Yes