Cos lettuce · Dongying, Shandong, China
When to plant cos lettuce in Dongying
Main outdoor window
13-27 Mar
The window this page is built around.
Timed from last spring frost
3 April
In Dongying, 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 Dongying
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
20 Feb - 6 Mar
Six weeks before your last frost, under cover or on a windowsill.
Sow for autumn
31 Jul - 21 Aug
Counting back 84 days from your first frost so the crop matures in time.
Sow direct
13-27 Mar
Three weeks before your last frost.
Sow direct
20 Mar - 3 Apr
Two weeks before your last frost.
Harvest
1 May - 31 Oct
Cos lettuce through the year
Against the frost risk in Dongying
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 Dongying.
The median frost-free season here is 224 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 Dongying
Other vegetables to time
Growing cos lettuce in Dongying
When should I plant cos lettuce in Dongying?
Aim for 13-27 Mar in an average year. If you would rather not gamble on the weather, wait until 25 Mar - 8 Apr - by then frost has finished in nine years out of ten.
When will cos lettuce be ready to harvest in Dongying?
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.