Japanese onion 'Ozawa'

Questions about Japanese onion 'Ozawa'

Does Japanese onion 'Ozawa' need sun or shade?

Japanese onion 'Ozawa' grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).

It wants ordinary well-drained soil, of average fertility, and little watering once settled.

What zones does Japanese onion 'Ozawa' grow in?

USDA zones 4 to 9. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does Japanese onion 'Ozawa' flower in my zone?

In zone 5 it flowers early October to early November. As an autumn flower it keeps much the same dates in every zone: it answers to shortening days and cool nights more than to the warmth of spring.

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should Japanese onion 'Ozawa' be planted?

8 in (20 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 10 in (25 cm), so a group knits into one patch.

It grows 10 in (25 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many Japanese onion 'Ozawa' plants do I need?

At 8 in apart, set out in staggered rows:

• 27 to fill 10 square feet (about 1 m²)
• 16 for a single row 10 ft (3 m) long
• 86 to fill a 4 × 8 ft bed on its own

In a mixed border, plant it as runs of three or five along the front (or one even row, in a formal bed).

In the bed above, the planner used 11 in three groups.

Is Japanese onion 'Ozawa' poisonous to dogs and cats?

Yes: moderate toxicity to dogs, cats and horses. Like all onions, it can damage red blood cells in dogs, cats and horses if eaten.

Is there a pet-safe plant like Japanese onion 'Ozawa'?

These come closest to doing what Japanese onion 'Ozawa' does, and no toxicity is recorded for them:

• Horned violet: the same job in a bed and the same colour; 4 in shorter, flowers mid April to late June.
• Carpathian bellflower 'Blue Clips': the same job in a bed and the same size; flowers late June to late August, blue, not purple.
• Balloon flower 'Sentimental Blue': the same job in a bed and the same size; flowers early July to late August, blue, not purple.

Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.

What flowers after Japanese onion 'Ozawa'?

Japanese onion 'Ozawa' is over by early November. These start as it finishes and carry the same spot on, so it never goes flat:

• Christmas rose 'Jacob': from late November to late December, 10 in tall.
• Bodnant viburnum 'Dawn': from early November to late December, 10 ft tall.

What does Japanese onion 'Ozawa' look like in winter?

Japanese onion 'Ozawa' dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.