Allium giganteum
Common Name: ornamental onion 
Type: Bulb
Family: Amaryllidaceae
Native Range: Central and western Asia
Zone: 5 to 8
Height: 3.00 to 5.00 feet
Spread: 1.50 to 2.00 feet
Bloom Time: May to June
Bloom Description: Purple
Sun: Full sun
Water: Medium
Maintenance: Medium
Flower: Showy, Good Cut, Good Dried
Leaf: Fragrant
Tolerate: Rabbit, Deer, Black Walnut


Easily grown in average, medium, well-drained soils in full sun. Best sited in locations sheltered from strong winds. Plant bulbs 5-6” deep and 9-12” apart in fall. Leaves will wither and disappear from the garden shortly after bloom. Mature bulbs may be dug up in fall, divided and replanted to increase size of a planting.

Noteworthy Characteristics

Allium giganteum, commonly called giant onion, is perhaps the tallest of the ornamental onions. It is a bulbous perennial (large bulbs to 2-3” diameter) which produces a basal rosette of grayish-green, strap-shaped leaves (to 18” long). From the center of each basal rosette rises a thick, naked, 3-4’ tall scape (stem) which is topped in late spring by a dense, globular, softball-sized, 5-6” diameter cluster (umbel) of tiny, star-shaped lilac-purple florets. Leaves and scapes smell like onions when bruised, but plant is not used for culinary purposes. Leaves begin to die back as plants begin flowering.

Genus name comes from the classical Latin name for garlic.

Specific epithet means giant.


No serious insect or disease problems. Susceptible to bulb rot. When in full bloom, scapes may need staking or other support, to be on the safe side, because high winds can do irreparable damage to a planting.


Dramatic border background plant which is best sited in groups of at least 5-7 bulbs.