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 25.
Step 1 · Sow
Start seeds indoors
Mar 4 – Mar 25
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 8 – Apr 29
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 22 – Jul 17
Picking runs until conditions turn against the crop.
Window
Days to maturity
75 – 100 d
Tokyo's 255-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 25
DEC 5
Common questions
When can I sow melon (cantaloupe/watermelon) outdoors in Tokyo?
Direct-sow around early April (Apr 8–Apr 29) in Tokyo, based on its local frost dates. Confidence 88%.
When will melon (cantaloupe/watermelon) be ready to harvest in Tokyo?
Expect to harvest from around late June (Jun 22–Jul 17) in Tokyo, based on its local frost dates. Confidence 79%.
When should I start melon (cantaloupe/watermelon) seeds indoors in Tokyo?
Start seeds indoors around early March (Mar 4–Mar 25) in Tokyo, based on its local frost dates. Confidence 84%.
When can I transplant melon (cantaloupe/watermelon) outdoors in Tokyo?
Transplant outdoors around early April (Apr 8–Apr 29) in Tokyo, based on its local frost dates. Confidence 88%.
How long is the growing season in Tokyo?
Tokyo has roughly 255 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 88/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.