Garden Fundamentals - Learn about plants and gardening

Allium thunbergii ‘Ozawa’

Allium thunbergii 'Ozawa', by Robert Pavlis

Allium thunbergii ‘Ozawa’, by Robert Pavlis

The last plant to start flowering in my zone 5 garden is  Allium thunbergii ‘Ozawa’, the Japanese onion. As I write this it is October 26, 2014 and we have not had a real hard frost yet which is very unusual. Most common fall flowering plants like mums are finished flowering but the Japanese onion is still going strong. It is not bothered by early frost or snow.

Allium thunbergii 'Ozawa', by Robert Pavlis

Allium thunbergii ‘Ozawa’, by Robert Pavlis

Most alliums flower in spring or summer. This one starts to make buds in early September but does not really open until early October, in zone 5. It then blooms for many weeks. I suspect the cold fall temperatures keep the buds and flowers fresh.

Some allium spread quickly by seed making them weedy plants, but not this one. It forms a nice clump and rarely self-seeds—probably because the seed does not have time to ripen before winter. In early summer it produces nice grass-like foliage that looks nice all year, developing an orange/red color after frost.

Allium thunbergii is also available as a white cultivar.

Allium thunbergii 'Ozawa', by Robert Pavlis

Allium thunbergii ‘Ozawa’, by Robert Pavlis

Allium thunbergii ‘Ozawa’

 (AL-ee-um thun-BERG-ee-eye)

Life Cycle: bulb/perennial

Height: 30cm (1ft)

Bloom Time: fall

Natural Range: Japan and Korea

Habitat: low mountains, forest margins, slopes and pastures to 1300 m

Synonyms:  none

Cultivation of Allium thunbergii ‘Ozawa’

Light: full sun to part shade

Soil: well drained

Water: not fussy, drought tolerant

USDA Hardiness Zone: 4– 9

Propagation: seed, division

If you like this post, please share .......
Robert Pavlis
Editor of GardenFundamentals.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Fundamentals an educational site that helps you understand your garden better.

5 Responses to 'Allium thunbergii ‘Ozawa’'

  1. jaspreet says:

    hi robert
    info u give are very useful and interesting. though i dont have a garden ,but front and backyard of my small urban house. gardening is my hobby .i used to grow veggies and flowers back home. hereupon i serve my hobby through planting a few perennials.
    robert do u send seeds or plants on order. i want to grow this plant -ozawa.how can i get this plant .
    thanks for ur helpful info.
    jaspreet,brampton

  2. Doug says:

    I love all things allium but each year it gets harder and harder to source interesting plants such as….”Ozawa”. Good luck finding this one.

Please let me know what you think - Leave a Reply