Coriander · Lanzhou, Gansu, China
When to plant coriander in Lanzhou
Main outdoor window
16-26 Apr
The window this page is built around.
Timed from last spring frost
30 April
In Lanzhou, on your chosen risk.
Ready to pick
31 May - 25 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 Lanzhou
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.
Sow for autumn
2-23 Jul
Counting back 84 days from your first frost so the crop matures in time.
Sow direct
16-26 Apr
Two weeks before your last frost.
Harvest
31 May - 25 Jun
Coriander through the year
Against the frost risk in Lanzhou
Why these dates
Sow every two weeks from two weeks before last frost. The autumn sowing lasts far longer than any summer one, and in mild climates overwinters.
Takes -5C and grows happily in cool weather. Heat, not frost, is what ends a coriander plant.
Seed packets and extension guides express timing as weeks either side of the last spring frost, because that is the only reference point that travels. Coriander are timed for direct sowing 2 weeks before it, and this page simply resolves those offsets against the frost date computed for Lanzhou.
The median frost-free season here is 168 days, against 45 to 70 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Growing coriander in Lanzhou
When should I plant coriander in Lanzhou?
Aim for 16-26 Apr in an average year. If you would rather not gamble on the weather, wait until 28 Apr - 8 May - by then frost has finished in nine years out of ten.
When will coriander be ready to harvest in Lanzhou?
Expect to start picking around 31 May - 25 Jun, based on 45 to 70 days to maturity from the planting date calculated for this location.
How much frost will coriander tolerate?
Takes -5C and grows happily in cool weather. Heat, not frost, is what ends a coriander plant.