Content Detail

Thunberg’s onion is a compact, clump-forming, perennial bulb that adds seasonal interest in the late fall garden. Clusters of lavender-pink flowers open above the grass-like foliage in late summer blooming into fall when the leaves turn a rusty orange color.

  • Family (English) Amaryllis
  • Family (botanic) Amaryllidaceae
  • Tree or plant type Perennial
  • Native locale Non-native
  • Size range Large plant (more than 24 inches), Medium plant (12-24 inches)
  • Light exposure Full sun (6 hrs direct light daily), Partial sun / shade (4-6 hrs light daily)
  • Hardiness zones Zone 4, Zone 5 (Chicago), Zone 6, Zone 7, Zone 8, Zone 9
  • Soil preference Moist, well-drained soil
  • Tolerances Alkaline soil, Dry sites, Occasional drought
  • Season of interest late fall, mid fall
  • Flower color and fragrance Pink, Purple
  • Shape or form Upright
  • Growth rate Fast

Size: 

A clump-forming bulb with narrow foliage reaching 12 to15 inches high.

Native geographic location and habitat: 

Found along wood edges of Japan, Korea, and China.

Attracts birds or pollinators: 

Butterflies, hummingbirds, bees and other pollinators.

Leaf description: 

The onion-scented, grass-like hollow leaves tend to relax on the ground before flowers emerge.  Leaves turn a rusty-orange after the first frost.

Flower description: 

Terminal umbels of nodding flower clusters open to purplish-pink flowers with protruding yellow-orange stamens.  This is one of the last onions to flower in the fall.

Fruit description: 

Because flowers appear so late in the fall plants rarely produce seeds

Plant care:

This perennial prefers full sun to part shade and  well-drained soil.  Divide clumps in early spring, just as new foliage is emerging.

List of pests, diseases, and tolerances: 

None serious. Does not tolerate wet soils. Tolerant of deer, rabbit, black walnut toxicity.

White Thunberg’s Onion (Allium thunbergii ‘Alba’): 

12 to 15 inches high, with white flowers

Ozawa Thunberg’s Onion (Allium thunbergii ‘Ozawa’):

Compact mounds of 6 to 12 inch-high foliage; pinkish-purple flowers

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