Water spinach · Köln, North Rhine-Westphalia, Germany
When to plant water spinach in Köln
Main outdoor window
1-22 May
The window this page is built around.
Timed from last spring frost
17 April
In Köln, 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 Köln
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
20 Mar - 10 Apr
Four weeks before your last frost, under cover or on a windowsill.
Sow direct
1-22 May
Two weeks after your last frost.
Plant out
1-22 May
Two weeks after your last frost.
Harvest
1 Jun - 31 Oct
Water spinach through the year
Against the frost risk in Köln
Why these dates
Start indoors four weeks before the last frost and plant out two weeks after it into soil kept permanently wet. Cut 20cm of tip growth and it regrows within a fortnight.
Damaged at about 5C, long before frost. It needs consistently warm nights and stops dead in a cool spell.
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. Water spinach are timed from 4 weeks before that frost for an indoor start, with planting out 2 weeks after it, and this page simply resolves those offsets against the frost date computed for Köln.
The median frost-free season here is 207 days, against 45 to 60 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.
Also in Köln
Other vegetables to time
Growing water spinach in Köln
When should I plant water spinach in Köln?
Aim for 1-22 May in an average year. If you would rather not gamble on the weather, wait until 17 May - 7 Jun - by then frost has finished in nine years out of ten.
When will water spinach be ready to harvest in Köln?
Expect to start picking around 1 Jun - 31 Oct, based on 45 to 60 days to maturity from the planting date calculated for this location.
How much frost will water spinach tolerate?
Damaged at about 5C, long before frost. It needs consistently warm nights and stops dead in a cool spell.