When to plant onion in Winnipeg
Onion is cold-hardy, so every date keys off Winnipeg's frost dates of May 25.
Step 1 · Sow
Start seeds indoors
Mar 16 – Apr 6
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
May 4 – May 25
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 2 – Aug 22
Picking runs until conditions turn against the crop.
Window
Days to maturity
90 – 110 d
Winnipeg's 118-day season leaves this much room.
Onion on Winnipeg'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 25
SEP 20
Common questions
When will onion be ready to harvest in Winnipeg?
Expect to harvest from around early August (Aug 2–Aug 22) in Winnipeg, based on its local frost dates. Confidence 65%.
When should I start onion seeds indoors in Winnipeg?
Start seeds indoors around mid March (Mar 16–Apr 6) in Winnipeg, based on its local frost dates. Confidence 68%.
When can I transplant onion outdoors in Winnipeg?
Transplant outdoors around early May (May 4–May 25) in Winnipeg, based on its local frost dates. Confidence 72%.
How long is the growing season in Winnipeg?
Winnipeg has roughly 118 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 Winnipeg's frost dates.
Confidence 72/100 · NASA POWER (modeled) · 1991–2020 · frost dates are probabilities, not guarantees.