Safe to Plant

Cos lettuce · Köln, North Rhine-Westphalia, Germany

When to plant cos lettuce in Köln

Main outdoor window

27 Mar - 10 Apr

The window this page is built around.

Timed from last spring frost

17 April

In Köln, on your chosen risk.

Ready to pick

1 May - 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

6-20 Mar

Six weeks before your last frost, under cover or on a windowsill.

Sow for autumn

28 Jul - 18 Aug

Counting back 84 days from your first frost so the crop matures in time.

Sow direct

27 Mar - 10 Apr

Three weeks before your last frost.

Sow direct

3-17 Apr

Two weeks before your last frost.

Harvest

1 May - 31 Oct

Sow in succession. A single sowing gives you a single glut. Sow a short row every 10 days through the window above and you get a steady supply instead.
Frost tolerance
Half-hardy
Damaged below
-3°C (26.6°F)
Days to maturity
55–70
Min soil temp
4.5°C (40.1°F)
Spacing
25 cm
Sowing depth
6 mm (0.2 in)
Sun
Partial

Cos lettuce through the year

Against the frost risk in Köln

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Cos lettuce

Frost risk Start indoors Autumn sowing Sow direct Plant out Harvest Today

Why these dates

Sow every ten days from six weeks before the last frost. The upright habit means it can go closer together than a heading type without rotting in the middle.

Takes about -3C. Outer leaves mark after a frost but the heart is usually untouched and can simply be trimmed to.

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. Cos lettuce 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 Köln.

The median frost-free season here is 207 days, against 55 to 70 days to maturity for this crop counted from sowing. That margin is what decides whether a late sowing is worth attempting.

See every crop timed for Köln →

Nearby

Cos lettuce in places close by

Bonn 24 km Düsseldorf 34 km Wuppertal 38 km Mönchengladbach 45 km Krefeld 53 km Duisburg 57 km

Also in Köln

Other vegetables to time

Tomatoes tender Lettuce half hardy Potatoes half hardy Courgettes tender Sweet peppers tender Carrots hardy Cucumbers tender Green beans tender Peas hardy Garlic very hardy Chilli peppers tender Sweetcorn tender

Growing cos lettuce in Köln

When should I plant cos lettuce in Köln?

Aim for 27 Mar - 10 Apr in an average year. If you would rather not gamble on the weather, wait until 12-26 Apr - by then frost has finished in nine years out of ten.

When will cos lettuce be ready to harvest in Köln?

Expect to start picking around 1 May - 31 Oct, based on 55 to 70 days to maturity from the planting date calculated for this location.

How much frost will cos lettuce tolerate?

Takes about -3C. Outer leaves mark after a frost but the heart is usually untouched and can simply be trimmed to.