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Ornamental Onion Allium giganteum

Other Common Name(s):

Previously known as:

  • Allium procerum
Phonetic Spelling
AL-ee-um jy-GAN-tee-um
This plant has low severity poison characteristics.
See below
Description

Ornamental Onion is a bulbous perennial characterized by its showy pink flowers and its garlic onion fragrance. It generally flowers in early summer and lasts 2-3 weeks. It is 35-50 inches tall with a large umbel of densely clumped florets. Its flowers are small, 6-parted, and in a cluster at the top of a naked stem. Although ornamental onion tolerates summer drought, it should be kept moist during the growing season.

Native to the Himalaya region, this allium can be found growing in forests, naturalized areas, and in disturbed areas where it has the potential to be weedy. In the landscape, it can be a cultivated perennial in flower beds where it does well with daylilies and low-growing grasses. It should be planted at a depth of 8” to the base of the bulb and 12” apart. A good rule for spacing ornamental onion is one bulb per square foot. For best results plant in the fall with access to full sunlight in well-drained soils. This plant will do well near the back of the border in groups of 5-9.

Pests, Insects, and Other Plant Problems: Overly damp conditions leave ornamental onions prone to fungal issues, including a black rot that appears on the leaves and bulbs, destroying the plant.

 

VIDEO Created by Elisabeth Meyer for "Edibles, Bulbs, and Houseplants" a plant identification course offered in partnership with Longwood Gardens.   

More information on Allium.

Profile Video:
See this plant in the following landscapes:
Cottage Garden
Cultivars / Varieties:
Tags:
#purple#fragrant#sun#bulb#showy flowers#poisonous#full sun#fragrant flowers#drought tolerant#perennial#perennial bulb#purple flowers#pink flowers#showy#weedy#fragrant leaves#cut flowers#colorful#spring flowers#accent plant#flower arrangements#bedding plant#herbaceous#well-drained soil#full sun flowers#perennial flowers#summer flowers#full sunlight#plant in fall#Tunicated bulb#exhibition bulbs#herbaceous perennial#large flowers#summer bulbs#sunshine#summer interest#cutting garden#spring interest#naturalized area#short lifespan#accent#small group plantings#perennials#spring flowering bulbs#small groups#pink#ebh#flowering#flower#summer garden#sun tolerant#ebh-g#flowers#large blooms
 
Cultivars / Varieties:
Tags:
#purple#fragrant#sun#bulb#showy flowers#poisonous#full sun#fragrant flowers#drought tolerant#perennial#perennial bulb#purple flowers#pink flowers#showy#weedy#fragrant leaves#cut flowers#colorful#spring flowers#accent plant#flower arrangements#bedding plant#herbaceous#well-drained soil#full sun flowers#perennial flowers#summer flowers#full sunlight#plant in fall#Tunicated bulb#exhibition bulbs#herbaceous perennial#large flowers#summer bulbs#sunshine#summer interest#cutting garden#spring interest#naturalized area#short lifespan#accent#small group plantings#perennials#spring flowering bulbs#small groups#pink#ebh#flowering#flower#summer garden#sun tolerant#ebh-g#flowers#large blooms
  • Attributes:
    Genus:
    Allium
    Species:
    giganteum
    Family:
    Alliaceae
    Life Cycle:
    Bulb
    Perennial
    Recommended Propagation Strategy:
    Division
    Seed
    Country Or Region Of Origin:
    Himalayas, Western and Central Asia
    Play Value:
    Attractive Flowers
    Colorful
    Fragrance
    Particularly Resistant To (Insects/Diseases/Other Problems):
    Typically not susceptible to animals. Drought tolerant.
    Edibility:
    Leaves, bulbs, and bulblets are edible. Gather leaves during spring and fall. Gather bulbs in the second year when they are large enough to use like cultivated onions. Flower stem bulblets are collected during the summer. However, the plant also has poisonous characteristics as noted in the "Poisonous to Humans" section of this record. Toxicity can depend on the age of the person or animal, the age of the plant, the part of the plant ingested, how much is ingested, whether the person or animal has sensitivities or allergies, whether it's eaten raw or cooked, and so forth. Consult with a medical professional for further details.
    Dimensions:
    Height: 1 ft. 0 in. - 6 ft. 0 in.
    Width: 1 ft. 0 in. - 2 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Bulb
    Herbaceous Perennial
    Perennial
    Poisonous
    Habit/Form:
    Erect
    Growth Rate:
    Medium
    Maintenance:
    Low
    Texture:
    Medium
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Soil Texture:
    Clay
    Loam (Silt)
    Sand
    Soil pH:
    Acid (<6.0)
    Alkaline (>8.0)
    Neutral (6.0-8.0)
    Soil Drainage:
    Good Drainage
    Available Space To Plant:
    Less than 12 inches
    NC Region:
    Coastal
    Mountains
    Piedmont
    USDA Plant Hardiness Zone:
    4a, 4b, 5b, 5a, 6a, 6b, 7a, 7b, 8b, 8a
  • Fruit:
    Fruit Type:
    Capsule
  • Flowers:
    Flower Color:
    Pink
    Purple/Lavender
    Flower Inflorescence:
    Umbel
    Flower Value To Gardener:
    Fragrant
    Good Cut
    Good Dried
    Long-lasting
    Flower Bloom Time:
    Spring
    Summer
    Flower Shape:
    Star
    Flower Petals:
    6 petals/rays
    Flower Size:
    < 1 inch
    Flower Description:
    The purple star-shaped flowers are small, 6-parted, and in a cluster 5-6 inches wide at the top of a naked stem. Blooms early summer in June-July and lasts 2-3 weeks. Good cut or dried.
  • Leaves:
    Leaf Color:
    Blue
    Gray/Silver
    Green
    Leaf Value To Gardener:
    Fragrant
    Leaf Type:
    Simple
    Leaf Arrangement:
    Rosulate
    Leaf Shape:
    Linear
    Leaf Margin:
    Entire
    Hairs Present:
    No
    Leaf Length:
    > 6 inches
    Leaf Width:
    3-6 inches
    Leaf Description:
    The leaves are long, slender, and strap-like, 2-3 ft. tall and 2-4 in. wide. They come up as a tight, upright cluster and then usually lie flat at the base of the plant. They have a fragrance that resembles garlic or onion. Slightly glaucous, which means that they are green with a tinge of blueish-gray. Often die down shortly after blooming has occurred.
  • Stem:
    Stem Color:
    Green
    Stem Is Aromatic:
    No
    Stem Surface:
    Smooth (glabrous)
    Stem Description:
    Sturdy green stem 3-4 feet tall
  • Landscape:
    Landscape Location:
    Naturalized Area
    Landscape Theme:
    Cottage Garden
    Cutting Garden
    Drought Tolerant Garden
    Design Feature:
    Accent
    Border
    Small groups
    Attracts:
    Butterflies
    Resistance To Challenges:
    Deer
    Drought
    Rabbits
    Problems:
    Poisonous to Humans
    Problem for Cats
    Problem for Dogs
    Short-lived
    Weedy
  • Poisonous to Humans:
    Poison Severity:
    Low
    Poison Symptoms:
    Poisonous through ingestion. Symptoms may include: nausea, vomiting, and diarrhea.
    Poison Toxic Principle:
    Sulfides
    Causes Contact Dermatitis:
    No
    Poison Part:
    Flowers
    Fruits
    Leaves
    Roots
    Seeds
    Stems