General description
Common Name: ornamental onion
Type: Bulb
Family: Alliaceae
Zone: 5 to 8
Native Range: Central Asia
Height: 3 to 5 feet
Spread: 1.5 to 2 feet
Bloom Time: May to June
Bloom Color: Purple
Bloom Description: Purple
Sun: Full sun
Water: Medium
Maintenance: Medium
Flowers: Showy Flowers
Leaves: Fragrant
Tolerates: Black Walnuts, Deer, Rabbits
Uses: Cut Flower, Dried Flower
Culture
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
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.
Problems
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.
Garden Uses
Dramatic border background plant which is best sited in groups of at least 5-7 bulbs.