When to plant onion in Nagoya
Onion is cold-hardy, so every date keys off Nagoya's frost dates of Mar 28.
Step 1 · Sow
Start seeds indoors
Jan 17 – Feb 7
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Mar 7 – Mar 28
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 5 – Jun 25
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Nagoya's 247-day season leaves this much room.
Onion on Nagoya'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
MAR 28
NOV 30
Common questions
When will onion be ready to harvest in Nagoya?
Expect to harvest from around early June (Jun 5–Jun 25) in Nagoya, based on its local frost dates. Confidence 76%.
When should I start onion seeds indoors in Nagoya?
Start seeds indoors around mid January (Jan 17–Feb 7) in Nagoya, based on its local frost dates. Confidence 80%.
When can I transplant onion outdoors in Nagoya?
Transplant outdoors around early March (Mar 7–Mar 28) in Nagoya, based on its local frost dates. Confidence 84%.
How long is the growing season in Nagoya?
Nagoya has roughly 247 frost-free days, which is enough time to grow onion to maturity outdoors.
The rule of thumb
Sow onion as soon as the soil is workable — it tolerates cool weather and light frost. Every date on this page is derived from that rule and Nagoya's frost dates.
Confidence 84/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.