When to plant onion in Fargo
Onion is cold-hardy, so every date keys off Fargo's frost dates of May 11.
Step 1 · Sow
Start seeds indoors
Mar 2 – Mar 23
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
May 13 – Jun 3
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 11 – Aug 31
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Fargo's 144-day season leaves this much room.
Onion on Fargo'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 11
OCT 2
Common questions
When will onion be ready to harvest in Fargo?
Expect to harvest from around mid August (Aug 11–Aug 31) in Fargo, based on its local frost dates. Confidence 80%.
When should I start onion seeds indoors in Fargo?
Start seeds indoors around early March (Mar 2–Mar 23) in Fargo, based on its local frost dates. Confidence 85%.
When can I transplant onion outdoors in Fargo?
Transplant outdoors around mid May (May 13–Jun 3) in Fargo, based on its local frost dates. Confidence 86%.
How long is the growing season in Fargo?
Fargo has roughly 144 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 Fargo's frost dates.
Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.