Safe to Plant

Bearded iris · Baoding, Hebei, China

When to sow bearded irises in Baoding

Main outdoor window

7 Nov - 18 Mar

The window this page is built around.

Timed from last spring frost

1 April

In Baoding, on your chosen risk.

Ready to pick

1 May - 30 Jun

If you plant at the start of the window.

The average last frost. Half of all years are later than this.

Step by step in Baoding

Each window is a range, not a single day. Earlier in the range buys you a longer season; later in it buys you a safer one.

Plant the rhizomes

7 Nov - 18 Mar

Any time the plant is dormant and the ground is neither frozen nor waterlogged: after leaf fall in autumn, or at the end of winter before growth restarts.

In flower

1 May - 30 Jun

Frost tolerance
Very-hardy
Damaged below
-30°C (-22°F)
First crop
Year 1
Hardy to
Zone 3a–9a
Spacing
40 cm
Sowing depth
20 mm (0.8 in)
Sun
Full

Bearded irises through the year

Against the frost risk in Baoding

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Frost risk Plant Harvest Today

Why these dates

Plant in late summer, six weeks or more before the first frost, with the top of the rhizome exposed to the sun and the roots spread below. Buried rhizomes rot instead of flowering. Divide every three or four years in midsummer, discarding the woody centre of the clump.

Hardy to -30C, with the exposed rhizome unharmed by frost. Winter wet is the real killer, so heavy soil needs grit or a raised bed. Needs a dry summer baking to flower well the following year.

Bearded irises are planted once and then left in place, so there is no sowing offset to resolve. What matters in Baoding is the shape of the year: this crop is dormant through the winter and is planted while it sleeps, any time between leaf fall in autumn and the restart of growth in spring, so long as the ground is neither frozen nor waterlogged. That is why the window below spans the cold months rather than sitting in the middle of the growing season.

Hardiness is not the obstacle here. Baoding is zone 7a, comfortably inside the range this crop is rated for, so an established plant should come through an average winter without protection.

Do not expect a crop in the first year. A plant set out now should give its first worthwhile pick around year 1, and will then produce every year after that, which is what makes the planting decision worth getting right the first time.

See every crop timed for Baoding →

Growing bearded irises in Baoding

When should I plant bearded irises in Baoding?

Aim for 7 Nov - 18 Mar in an average year. If you would rather not gamble on the weather, wait until 25 Oct - 30 Mar - by then frost has finished in nine years out of ten.

When will bearded irises be ready to harvest in Baoding?

Expect to start picking around 1 May - 30 Jun, based on 150 to 190 days to maturity from the planting date calculated for this location.

How much frost will bearded irises tolerate?

Hardy to -30C, with the exposed rhizome unharmed by frost. Winter wet is the real killer, so heavy soil needs grit or a raised bed. Needs a dry summer baking to flower well the following year.