Rapini · Chōfu, Tokyo, Japan
When to plant rapini in Chōfu
Main outdoor window
18 Mar - 8 Apr
The window this page is built around.
Timed from last spring frost
1 April
In Chōfu, on your chosen risk.
Ready to pick
1 May - 30 Nov
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 Chōfu
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 for autumn
5-26 Sep
Counting back 69 days from your first frost so the crop matures in time.
Sow direct
18 Mar - 8 Apr
Two weeks before your last frost.
Harvest
1 May - 30 Nov
Rapini through the year
Against the frost risk in Chōfu
Why these dates
Sow from two weeks before the last frost and again from late summer. Warm weather pushes it into flower before the plant has any bulk, so the autumn sowing is the better one.
Hardy to about -6C. Cold weather is what keeps the buds tight, so a frosty autumn produces the best heads.
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. Rapini are timed for direct sowing 2 weeks before it, and this page simply resolves those offsets against the frost date computed for Chōfu.
The median frost-free season here is 247 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.
Also in Chōfu
Other vegetables to time
Growing rapini in Chōfu
When should I plant rapini in Chōfu?
Aim for 18 Mar - 8 Apr in an average year. If you would rather not gamble on the weather, wait until 26 Mar - 16 Apr - by then frost has finished in nine years out of ten.
When will rapini be ready to harvest in Chōfu?
Expect to start picking around 1 May - 30 Nov, based on 40 to 55 days to maturity from the planting date calculated for this location.
How much frost will rapini tolerate?
Hardy to about -6C. Cold weather is what keeps the buds tight, so a frosty autumn produces the best heads.