When to plant sweet potato in Tokyo
Sweet potato is frost-tender, so every date keys off Tokyo's last spring frost of Mar 25.
Step 1 · Plant
Transplant outdoors
Apr 15 – May 6
Once frost risk has passed and nights stay mild.
Step 2 · Harvest
Harvest window
Jul 14 – Aug 13
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 120 d
Tokyo's 255-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 25
DEC 5
Common questions
When will sweet potato be ready to harvest in Tokyo?
Expect to harvest from around mid July (Jul 14–Aug 13) in Tokyo, based on its local frost dates. Confidence 79%.
When can I transplant sweet potato outdoors in Tokyo?
Transplant outdoors around mid April (Apr 15–May 6) 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 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 88/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.