Cavolo nero · Chōfu, Tokyo, Japan
When to plant cavolo nero 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 Sep - 31 Mar
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.
Start indoors
18 Feb - 11 Mar
Six weeks before your last frost, under cover or on a windowsill.
Sow direct
18 Mar - 8 Apr
Two weeks before your last frost.
Transplant
18 Mar - 8 Apr
Two weeks before your last frost.
Harvest
1 Sep - 31 Mar
Cavolo nero through the year
Against the frost risk in Chōfu
Why these dates
Treated exactly like kale: sow from six weeks before the last frost for summer picking, and again in midsummer for the plants that carry you through winter.
Hardy to about -12C. Repeated frosts convert starch to sugar and the leaf becomes noticeably sweeter, so the winter crop is the better one.
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. Cavolo nero are timed from 6 weeks before that frost for an indoor start, with planting out 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 60 to 80 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 cavolo nero in Chōfu
When should I plant cavolo nero 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 cavolo nero be ready to harvest in Chōfu?
Expect to start picking around 1 Sep - 31 Mar, based on 60 to 80 days to maturity from the planting date calculated for this location.
How much frost will cavolo nero tolerate?
Hardy to about -12C. Repeated frosts convert starch to sugar and the leaf becomes noticeably sweeter, so the winter crop is the better one.