When to plant sweet potato in Tokyo
Sweet potato is frost-tender, so every date keys off Tokyo's last spring frost of Mar 28.
Step 1 · Plant
Transplant outdoors
May 26 – Jun 16
Once frost risk has passed and nights stay mild.
Step 2 · Harvest
Harvest window
Aug 24 – Sep 23
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 120 d
Tokyo's 258-day season leaves this much room.
Sweet potato 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 will sweet potato be ready to harvest in Tokyo?
Expect to harvest from around late August (Aug 24–Sep 23) in Tokyo, based on its local frost dates. Confidence 40%.
When can I transplant sweet potato outdoors in Tokyo?
Transplant outdoors around late May (May 26–Jun 16) 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 sweet potato to maturity outdoors.
The rule of thumb
Sow sweet potato 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.