Welsh onion · Chũ, Bac Ninh, Vietnam
When to plant welsh onions in Chũ
Main outdoor window
11 Dec - 1 Jan
The window this page is built around.
Timed from last spring frost
8 January
In Chũ, on your chosen risk.
Ready to pick
1 Apr - 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 Chũ
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
11 Dec - 1 Jan
Four weeks before your last frost.
Plant out
22 Jan - 12 Feb
Two weeks after your last frost.
Harvest
1 Apr - 31 Oct
Welsh onions through the year
Against the frost risk in Chũ
Why these dates
Very hardy, to -20C, and one of the first alliums to grow again in spring.
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. Welsh onions are timed with planting out 2 weeks after it, and this page simply resolves those offsets against the frost date computed for Chũ.
Chũ sits in zone 10a, which is milder than this crop wants, and a winter that never really arrives is its own problem. The dates below still describe the right time of year; the open question is survival rather than timing.
Do not expect a crop in the first year. A plant set out now should give its first worthwhile pick around year 1, and will then produce every year after that, which is what makes the planting decision worth getting right the first time.
Also in Chũ
Other vegetables to time
Growing welsh onions in Chũ
When should I plant welsh onions in Chũ?
Aim for 11 Dec - 1 Jan in an average year. If you would rather not gamble on the weather, wait until 25 Dec - 15 Jan - by then frost has finished in nine years out of ten.
When will welsh onions be ready to harvest in Chũ?
Expect to start picking around 1 Apr - 31 Oct, based on 80 to 100 days to maturity from the planting date calculated for this location.
How much frost will welsh onions tolerate?
Very hardy, to -20C, and one of the first alliums to grow again in spring.