Cos lettuce · Zhu Cheng City, Shandong, China
When to plant cos lettuce in Zhu Cheng City
Main outdoor window
10-24 Mar
The window this page is built around.
Timed from last spring frost
31 March
In Zhu Cheng City, 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 Zhu Cheng City
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
17 Feb - 3 Mar
Six weeks before your last frost, under cover or on a windowsill.
Sow for autumn
30 Jul - 20 Aug
Counting back 84 days from your first frost so the crop matures in time.
Sow direct
10-24 Mar
Three weeks before your last frost.
Sow direct
17-31 Mar
Two weeks before your last frost.
Harvest
1 May - 31 Oct
Cos lettuce through the year
Against the frost risk in Zhu Cheng City
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 Zhu Cheng City.
The median frost-free season here is 226 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 Zhu Cheng City
Other vegetables to time
Growing cos lettuce in Zhu Cheng City
When should I plant cos lettuce in Zhu Cheng City?
Aim for 10-24 Mar in an average year. If you would rather not gamble on the weather, wait until 21 Mar - 4 Apr - by then frost has finished in nine years out of ten.
When will cos lettuce be ready to harvest in Zhu Cheng City?
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.