Common Name: ornamental onion
Type: Bulb
Family: Amaryllidaceae
Zone: 5 to 8
Height: 1.50 to 2.50 feet
Spread: 1.00 to 1.50 feet
Bloom Time: May
Bloom Description: Deep lavender
Sun: Full sun
Water: Dry to medium
Maintenance: Low
Suggested Use: Naturalize
Flower: Showy
Leaf: Fragrant
Attracts: Butterflies
Tolerate: Deer, Drought, Black Walnut
Culture
Easily grown in average, dry to medium moisture, well-drained soils in full sun to part shade. Best in full sun, but appreciates some light afternoon shade in hot summer climates. Tolerates a wide range of soils. Performs well in sandy soils. Add compost to clay soils, as needed, to improve drainage. Bulbs are best planted in fall. Deadhead after blooming to discourage unwanted seeding in the garden. Divide in the spring or early fall.
'Globemaster' is a sterile hybrid that does not produce seed, so self-seeding is obviously not a concern. Plant new bulbs 4-6" deep (3 times bulb diameter) and 12" apart in fall. Bulbs of established plants may be dug, divided and replanted in late summer to early fall after foliage has died down.
Noteworthy Characteristics
The genus Allium contains over 700 species of bulbous or rhizomatous plants. All possess oniony smelling flowers and foliage. Some species are grown for culinary purposes and others for ornamental purposes. Plants typically produce showy flower umbels on naked scapes rising above a clump of linear grass-like leaves. Ornamental alliums generally range in height from 3” to 4-6’ tall.
Genus name comes from the classical Latin name for garlic.
'Globemaster' is a hybrid cross between A. christophii and A. macleanii. It is a bulbous perennial that is ornamentally grown for its spring bloom of spherical, deep lavender flower heads. Strap-shaped, gray-green, basal leaves form a clump of foliage in spring. As the leaves begin to wither in mid-spring, stout flowering stems rise to 20-30" tall topped with huge, globular, deep lavender to silver-purple flower heads (terminal umbels to 6-10" in diameter) packed with individual star-shaped florets which collectively display a metallic sheen. Flowers appear in an impressive, long-lasting, spring bloom (May in St. Louis) in which new florets continue to develop as the original ones fade. Flower heads dry after bloom and remain ornamental in the garden well into summer. Flowers generally lack fragrance.
Problems
Bulb rot may occur in overly moist soils. Watch for mildew, rust and leaf spots. Thrips are an occasional problem. Deer and rabbits tend to avoid this plant.
Plants may colonize over time, but are not considered to be invasive.
Uses
Grow as a striking accent.