Ornamental Onions are fast-growing perennials that appear for only a few months out of the year. Their enormous purple, pink, or white umbels create a dramatic appearance in gardens.
Allium giganteum (Ornamental Onion, Allium)
Deciduous: Yes, the foliage dies once flowering begins in May.
Hardiness Zones: 5-8
Height: 1.0-1.5 meters (3-5 feet) tall
Diameter: 50-60 centimeters (18-24 inches) across at maturity
Growth Rate: fast
Root System: likely fibrous
Subspecies: var. ‘Twinkling Star’
Tolerates: Black Walnut (Juglans nigra) toxins (juglones), herbivores (deer and rabbits)
Problems (major): no major pest issues
Problems (minor): Winds, especially when strong, easily knock over the inflorescences (known as scapes). Bulb rot may kill ornamental onions.
Poisonous: potentially toxic (especially to dogs) if consumed in large quantities
Soil requirements: performs best in moderate/medium/loamy, well-drained soils (tolerates most pH levels)
Air requirements: not sufficiently researched
Watering requirement: moderate
Sun requirement: prefers full sun, survives in some shade
Leaf shape: basal, strap-shaped, light-green to gray-green
Leaf size: less than 12 inches in diameter per leaf
Flower structure: The scapes grow up to 1.5 meters (5 feet) tall with an umbel (globular cluster of individual flowers) consisting of tiny (sometimes white or pink) purple, star-shaped flowers (known as florets).
Flowering frequency: blooms annually in May-June
Bulb/tuber: bulb up to 3 inches in diameter
The large cluster of florets (forming an umbel) are large and spectacular. Although visible above-ground for only a short amount of time, these are commonly grown in gardens for their flowers.
These are commonly planted as ornamentals.
All of the images provided were taken by me. They may be used for educational/informational purposes only, provided that this article/online journal is appropriately cited first.