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Allium thunbergii (Japanese onion)

Allium thunbergii Photo/Illustration: Chris Curless


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Hardiness Zones: 1 2 3 4 5 6 7 8 9 10 11
Botanical Name: Allium thunbergii AL-ee-um thun-BER-jee-eye Common Name: Japanese onion Genus: Allium
This is the last of the ornamental onions to flower, when mop-like heads of rose-purple flowers appear with orange anthers. The flowers are impervious to frost or snow. Superior cultivars include ‘Ozawa’, with larger purple flower heads than the species. A white-flowered form known as A. thunbergii ‘Alba’ is a splendid plant, with cup-shaped florets sporting white stamens, yellow anthers, and green centers.
 Care: Provide full sun to part shade and average, well-drained soil.
 Propagation: Sow seed in spring in containers or in situ. Divide clump-forming  plants in spring.
 Problems: Bulb rot in damp conditions. Onion fly and thrips.
Height 6 in. to 12 in.
Light Full Sun to Part Shade
Moisture Medium Moisture
Maintenance Low
Tolerance Deer Tolerant
Characteristics Attracts Butterflies; Attracts Hummingbirds; Fragrant Foliage
Bloom Time Fall; Late Summer; Summer
Flower Color Purple/ Lavender Flower; Red Flower
Uses Beds and Borders, Naturalizing
Style Rock Garden
Seasonal Interest Summer Interest, Fall Interest

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