Sweetcorn · Kaech’ŏn, South Pyongan, North Korea
When to plant sweetcorn in Kaech’ŏn
Main outdoor window
20 Apr - 4 May
The window this page is built around.
Timed from last spring frost
13 April
In Kaech’ŏn, on your chosen risk.
Ready to pick
19 Jun - 29 Jul
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 Kaech’ŏn
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 direct
20 Apr - 4 May
One week after your last frost.
Harvest
19 Jun - 29 Jul
Sweetcorn through the year
Against the frost risk in Kaech’ŏn
Why these dates
Seed rots in cold wet soil. Sowing a week after last frost into 15C soil beats sowing on the frost date into 10C soil almost every time.
Seedlings survive a very light frost if the growing point is still below soil level, but growth stalls. Mature plants are killed outright.
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. Sweetcorn are timed for direct sowing 1 weeks after it, and this page simply resolves those offsets against the frost date computed for Kaech’ŏn.
The median frost-free season here is 200 days, against 60 to 100 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Kaech’ŏn
Other vegetables to time
Growing sweetcorn in Kaech’ŏn
When should I plant sweetcorn in Kaech’ŏn?
Aim for 20 Apr - 4 May in an average year. If you would rather not gamble on the weather, wait until 1-15 May - by then frost has finished in nine years out of ten.
When will sweetcorn be ready to harvest in Kaech’ŏn?
Expect to start picking around 19 Jun - 29 Jul, based on 60 to 100 days to maturity from the planting date calculated for this location.
How much frost will sweetcorn tolerate?
Seedlings survive a very light frost if the growing point is still below soil level, but growth stalls. Mature plants are killed outright.