When to plant melon (cantaloupe/watermelon) in Tokyo
Melon (cantaloupe/watermelon) is frost-tender, so every date keys off Tokyo's last spring frost of Mar 28.
Step 1 · Sow
Start seeds indoors
Mar 19 – Apr 9
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jun 19 – Jul 10
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Sep 2 – Sep 27
Picking runs until conditions turn against the crop.
Window
Days to maturity
75 – 100 d
Tokyo's 258-day season leaves this much room.
Melon (cantaloupe/watermelon) on Tokyo'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
MAR 28
DEC 11
Common questions
When can I sow melon (cantaloupe/watermelon) outdoors in Tokyo?
Direct-sow around mid June (Jun 19–Jul 10) in Tokyo, based on its local frost dates. Confidence 44%.
When will melon (cantaloupe/watermelon) be ready to harvest in Tokyo?
Expect to harvest from around early September (Sep 2–Sep 27) in Tokyo, based on its local frost dates. Confidence 40%.
When should I start melon (cantaloupe/watermelon) seeds indoors in Tokyo?
Start seeds indoors around mid March (Mar 19–Apr 9) in Tokyo, based on its local frost dates. Confidence 43%.
When can I transplant melon (cantaloupe/watermelon) outdoors in Tokyo?
Transplant outdoors around mid June (Jun 19–Jul 10) in Tokyo, based on its local frost dates. Confidence 44%.
How long is the growing season in Tokyo?
Tokyo has roughly 258 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 Tokyo's frost dates.
Confidence 45/100 · Curated · based on NASA POWER (modeled) 1991–2020 · frost dates are probabilities, not guarantees.