Choy sum · Washington, District of Columbia, United States
When to plant choy sum in Washington
Main outdoor window
10-24 Apr
The window this page is built around.
Timed from last spring frost
3 April
In Washington, on your chosen risk.
Ready to pick
1 Jun - 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 Washington
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
10-24 Apr
One week after your last frost.
Harvest
1 Jun - 31 Oct
Choy sum through the year
Against the frost risk in Washington
Why these dates
Sow every two weeks from just after the last frost. Six weeks from seed to cutting means it slots into gaps between slower crops all season.
Damaged around -4C. Autumn sowings under cover crop well into early winter in mild climates.
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. Choy sum are timed for direct sowing 1 weeks after it, and this page simply resolves those offsets against the frost date computed for Washington.
The median frost-free season here is 221 days, against 40 to 55 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Nearby
Choy sum in places close by
Also in Washington
Other vegetables to time
Growing choy sum in Washington
When should I plant choy sum in Washington?
Aim for 10-24 Apr in an average year. If you would rather not gamble on the weather, wait until 20 Apr - 4 May - by then frost has finished in nine years out of ten.
When will choy sum be ready to harvest in Washington?
Expect to start picking around 1 Jun - 31 Oct, based on 40 to 55 days to maturity from the planting date calculated for this location.
How much frost will choy sum tolerate?
Damaged around -4C. Autumn sowings under cover crop well into early winter in mild climates.