Common Name: ornamental onion
Type: Bulb
Family: Amaryllidaceae
Zone: 5 to 8
Height: 1.00 to 1.50 feet
Spread: 1.00 to 1.50 feet
Bloom Time: July to August
Bloom Description: Rose-purple
Sun: Full sun to part shade
Water: Dry to medium
Maintenance: Low
Flower: Showy, Good Cut
Attracts: Butterflies
Tolerate: Rabbit, Deer, Drought, Dry Soil
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.
Although ‘Millenium’ is a true bulb on a stout rhizome, it forms a clump which can be lifted and divided in either spring or fall. Unlike many of the ornamental alliums, this hybrid is a clump-former which has reduced fertility such that on a normal flower head full of little individual florets, about 50%-70% of those florets will produce seed capsules with viable seed inside. If self-sowing is not wanted, dead-head after flowering.
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.
‘Millenium’ is a hybrid ornamental onion developed by allium breeder Mark McDonough. Its hybrid parentage is unknown, but likely includes some A. nutans. Each bulb typically produces an upright foliage clump of slender, somewhat flattened, broad linear, grass-like, glossy deep green leaves to 6-12” tall in spring. Unbranched naked scapes rise above the foliage clump to as much as 18-20” tall by mid-summer, each scape being topped by a showy 2-inch spherical umbel of rose purple florets. Flowers typically bloom mid to late summer (July-August). The flowers are suitable for fresh cut arrangements. Although all parts of this plant have an oniony smell and taste when cut or bruised, this hybrid is considered to be an ornamental and is not used for culinary purposes.
Cultivar name suffers from a minor spelling problem. It is often spelled ‘Millennium’, but Mark McDonough apparently registered it under the name of ‘Millenium’.
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.
Uses
A striking accent for mixed borders and cottage gardens.