Celeriac · Hanam, Gyeonggi-do, South Korea
When to plant celeriac in Hanam
Main outdoor window
26 Apr - 17 May
The window this page is built around.
Timed from last spring frost
12 April
In Hanam, on your chosen risk.
Ready to pick
14 Aug - 13 Sep
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 Hanam
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
1-22 Feb
Ten weeks before your last frost, under cover or on a windowsill.
Plant out
26 Apr - 17 May
Two weeks after your last frost.
Harvest
14 Aug - 13 Sep
Celeriac through the year
Against the frost risk in Hanam
Why these dates
Start indoors 10 weeks before the last frost and plant out after it, keeping the crown at soil level rather than buried. Remove the lower leaves in late summer so the root swells cleanly.
Stands to about -8C in the ground and improves with a touch of frost, so it can be left and lifted as needed well into winter.
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. Celeriac are timed from 10 weeks before that frost for an indoor start, with planting out 2 weeks after it, and this page simply resolves those offsets against the frost date computed for Hanam.
The median frost-free season here is 199 days, against 110 to 140 days to maturity for this crop counted from planting out. That margin is what decides whether a late sowing is worth attempting.
Also in Hanam
Other vegetables to time
Growing celeriac in Hanam
When should I plant celeriac in Hanam?
Aim for 26 Apr - 17 May in an average year. If you would rather not gamble on the weather, wait until 9-30 May - by then frost has finished in nine years out of ten.
When will celeriac be ready to harvest in Hanam?
Expect to start picking around 14 Aug - 13 Sep, based on 110 to 140 days to maturity from the planting date calculated for this location.
How much frost will celeriac tolerate?
Stands to about -8C in the ground and improves with a touch of frost, so it can be left and lifted as needed well into winter.