Radicchio · Bonn, North Rhine-Westphalia, Germany
When to plant radicchio in Bonn
Main outdoor window
19 May - 9 Jun
The window this page is built around.
Timed from last spring frost
21 April
In Bonn, on your chosen risk.
Ready to pick
1 Sep - 31 Dec
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 Bonn
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
19 May - 9 Jun
Four weeks after your last frost.
Harvest
1 Sep - 31 Dec
Radicchio through the year
Against the frost risk in Bonn
Why these dates
Sow around four weeks after the last frost so heading coincides with cooling autumn weather. Spring sowings stay green, loose and unpleasantly bitter.
Hardy to roughly -8C. Some traditional types are cut back after the first frosts and regrow a second, tighter head.
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. Radicchio are timed for direct sowing 4 weeks after it, and this page simply resolves those offsets against the frost date computed for Bonn.
The median frost-free season here is 199 days, against 80 to 110 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Bonn
Other vegetables to time
Growing radicchio in Bonn
When should I plant radicchio in Bonn?
Aim for 19 May - 9 Jun in an average year. If you would rather not gamble on the weather, wait until 2-23 Jun - by then frost has finished in nine years out of ten.
When will radicchio be ready to harvest in Bonn?
Expect to start picking around 1 Sep - 31 Dec, based on 80 to 110 days to maturity from the planting date calculated for this location.
How much frost will radicchio tolerate?
Hardy to roughly -8C. Some traditional types are cut back after the first frosts and regrow a second, tighter head.