When to plant onion in Green Bay
Onion is cold-hardy, so every date keys off Green Bay's frost dates of May 4.
Step 1 · Sow
Start seeds indoors
Feb 23 – Mar 16
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
May 12 – Jun 2
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 10 – Aug 30
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Green Bay's 152-day season leaves this much room.
Onion on Green Bay'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
MAY 4
OCT 5
Common questions
When will onion be ready to harvest in Green Bay?
Expect to harvest from around early August (Aug 10–Aug 30) in Green Bay, based on its local frost dates. Confidence 79%.
When should I start onion seeds indoors in Green Bay?
Start seeds indoors around late February (Feb 23–Mar 16) in Green Bay, based on its local frost dates. Confidence 84%.
When can I transplant onion outdoors in Green Bay?
Transplant outdoors around mid May (May 12–Jun 2) in Green Bay, based on its local frost dates. Confidence 85%.
How long is the growing season in Green Bay?
Green Bay has roughly 152 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 Green Bay's frost dates.
Confidence 88/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.