When to plant leek in Cologne
Leek is cold-hardy, so every date keys off Cologne's frost dates of Mar 26.
Step 1 · Sow
Start seeds indoors
Jan 15 – Feb 5
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Mar 18 – Apr 8
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 26 – Jul 16
Picking runs until conditions turn against the crop.
Window
Days to maturity
100 – 120 d
Cologne's 238-day season leaves this much room.
Leek on Cologne's growing year
Frost-bounded season with crops mapped onto the 12-month axis.
Frost risk Growing Harvest
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
FROST
FROST
MAR 26
NOV 17
Common questions
When will leek be ready to harvest in Cologne?
Expect to harvest from around late June (Jun 26–Jul 16) in Cologne, based on its local frost dates. Confidence 80%.
When should I start leek seeds indoors in Cologne?
Start seeds indoors around mid January (Jan 15–Feb 5) in Cologne, based on its local frost dates. Confidence 85%.
When can I transplant leek outdoors in Cologne?
Transplant outdoors around mid March (Mar 18–Apr 8) in Cologne, based on its local frost dates. Confidence 86%.
How long is the growing season in Cologne?
Cologne has roughly 238 frost-free days, which is enough time to grow leek to maturity outdoors.
The rule of thumb
Sow leek as soon as the soil is workable — it tolerates cool weather and light frost. Every date on this page is derived from that rule and Cologne's frost dates.
Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.