Cos lettuce · Ürümqi, Xinjiang, China
When to plant cos lettuce in Ürümqi
Main outdoor window
23 Mar - 6 Apr
The window this page is built around.
Timed from last spring frost
13 April
In Ürümqi, on your chosen risk.
Ready to pick
1 May - 31 Oct
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 Ürümqi
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.
Start indoors
2-16 Mar
Six weeks before your last frost, under cover or on a windowsill.
Sow for autumn
9-30 Jul
Counting back 84 days from your first frost so the crop matures in time.
Sow direct
23 Mar - 6 Apr
Three weeks before your last frost.
Sow direct
30 Mar - 13 Apr
Two weeks before your last frost.
Harvest
1 May - 31 Oct
Cos lettuce through the year
Against the frost risk in Ürümqi
Why these dates
Sow every ten days from six weeks before the last frost. The upright habit means it can go closer together than a heading type without rotting in the middle.
Takes about -3C. Outer leaves mark after a frost but the heart is usually untouched and can simply be trimmed to.
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. Cos lettuce are timed from 6 weeks before that frost for an indoor start, with planting out 2 weeks before it, and this page simply resolves those offsets against the frost date computed for Ürümqi.
The median frost-free season here is 192 days, against 55 to 70 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Ürümqi
Other vegetables to time
Growing cos lettuce in Ürümqi
When should I plant cos lettuce in Ürümqi?
Aim for 23 Mar - 6 Apr in an average year. If you would rather not gamble on the weather, wait until 4-18 Apr - by then frost has finished in nine years out of ten.
When will cos lettuce be ready to harvest in Ürümqi?
Expect to start picking around 1 May - 31 Oct, based on 55 to 70 days to maturity from the planting date calculated for this location.
How much frost will cos lettuce tolerate?
Takes about -3C. Outer leaves mark after a frost but the heart is usually untouched and can simply be trimmed to.