When to plant leek in Sapporo
Leek is cold-hardy, so every date keys off Sapporo's frost dates of May 5.
Step 1 · Sow
Start seeds indoors
Feb 24 – Mar 17
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 21 – May 12
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 30 – Aug 19
Picking runs until conditions turn against the crop.
Window
Days to maturity
100 – 120 d
Sapporo's 173-day season leaves this much room.
Leek on Sapporo'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
MAY 5
OCT 25
Common questions
When will leek be ready to harvest in Sapporo?
Expect to harvest from around late July (Jul 30–Aug 19) in Sapporo, based on its local frost dates. Confidence 76%.
When should I start leek seeds indoors in Sapporo?
Start seeds indoors around late February (Feb 24–Mar 17) in Sapporo, based on its local frost dates. Confidence 80%.
When can I transplant leek outdoors in Sapporo?
Transplant outdoors around late April (Apr 21–May 12) in Sapporo, based on its local frost dates. Confidence 84%.
How long is the growing season in Sapporo?
Sapporo has roughly 173 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 Sapporo's frost dates.
Confidence 84/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.