When to plant melon (cantaloupe/watermelon) in Sapporo
Melon (cantaloupe/watermelon) is frost-tender, so every date keys off Sapporo's last spring frost of May 5.
Step 1 · Sow
Start seeds indoors
Apr 14 – May 5
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
May 19 – Jun 9
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 2 – Aug 27
Picking runs until conditions turn against the crop.
Window
Days to maturity
75 – 100 d
Sapporo's 173-day season leaves this much room.
Melon (cantaloupe/watermelon) 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 can I sow melon (cantaloupe/watermelon) outdoors in Sapporo?
Direct-sow around mid May (May 19–Jun 9) in Sapporo, based on its local frost dates. Confidence 84%.
When will melon (cantaloupe/watermelon) be ready to harvest in Sapporo?
Expect to harvest from around early August (Aug 2–Aug 27) in Sapporo, based on its local frost dates. Confidence 76%.
When should I start melon (cantaloupe/watermelon) seeds indoors in Sapporo?
Start seeds indoors around mid April (Apr 14–May 5) in Sapporo, based on its local frost dates. Confidence 80%.
When can I transplant melon (cantaloupe/watermelon) outdoors in Sapporo?
Transplant outdoors around mid May (May 19–Jun 9) 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 melon (cantaloupe/watermelon) to maturity outdoors.
The rule of thumb
Sow melon (cantaloupe/watermelon) 6–8 weeks before your last spring frost; plant out 2–3 weeks after it. 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.