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ALLIUM caeruleum

Image of Allium caeruleum

James H. Schutte

Family

Liliaceae

Botanical Name

ALLIUM caeruleum

Plant Common Name

Blue Ornamental Onion

General Description

Blue ornamental onion is a perennial bulb grown for its small clusters of azure blue, star-shaped flowers. In late spring to early summer, each plant puts forth multiple leafless stems topped with one flower cluster. The green strap-like foliage appears before plants bloom and often dies back before flowers the appear. This onion has a lightly oniony fragrance when its leaves or stems are crushed.

Blue ornamental onion is originates from the mountains of northern and Central Asia where it grows in sharply drained soil and full sun. Plant it in fall four to five inches deep to the base of the bulb. Rot can result if planted in overly moist ground, so make sure your soil’s drainage is good. This allium has a subtle beauty and looks best when planted among other showy bulbs and perennials in the garden.

Characteristics

  • AHS Heat Zone

    10 - 1

  • USDA Hardiness Zone

    4 - 10

  • Sunset Zone

    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

    Bulb or Corm or Tuber

  • Sun Exposure

    Full Sun

  • Height

    12"-24" / 30.5cm - 61.0cm

  • Width

    8"-12" / 20.3cm - 30.5cm

  • Bloom Time

    Late Spring, Early Summer, Summer

  • Native To

    Asia, Central Asia

Growing Conditions

  • Soil pH

    Neutral

  • Soil Drainage

    Well Drained

  • Soil type

    Loam, Sand

  • Growth Rate

    Medium

  • Water Requirements

    Average Water

  • Seasonal Interest

    Spring, Summer

Ornamental Features

  • Flower Interest

    Showy

  • Flower Color

    Light Blue, Blue Violet

  • Foliage Color (Spring)

    Green

  • Foliage Color (Summer)

    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

    Alpine, Cutflower, Mixed Border, Rock Garden / Wall

  • Sharp or Has Thorns

    No

  • Invasive

    No

  • Self-Sowing

    Yes