When to plant leek in Sapporo
Leek is cold-hardy, so every date keys off Sapporo's frost dates of May 12.
Step 1 · Sow
Start seeds indoors
Mar 3 – Mar 24
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
May 9 – May 30
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 17 – Sep 6
Picking runs until conditions turn against the crop.
Window
Days to maturity
100 – 120 d
Sapporo's 166-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 12
OCT 20
Common questions
When will leek be ready to harvest in Sapporo?
Expect to harvest from around mid August (Aug 17–Sep 6) in Sapporo, based on its local frost dates. Confidence 40%.
When should I start leek seeds indoors in Sapporo?
Start seeds indoors around early March (Mar 3–Mar 24) in Sapporo, based on its local frost dates. Confidence 43%.
When can I transplant leek outdoors in Sapporo?
Transplant outdoors around early May (May 9–May 30) in Sapporo, based on its local frost dates. Confidence 44%.
How long is the growing season in Sapporo?
Sapporo has roughly 166 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 45/100 · Curated · based on NASA POWER (modeled) 1991–2020 · frost dates are probabilities, not guarantees.