When to plant winter squash / pumpkin in Ottawa
Winter squash / Pumpkin is frost-tender, so every date keys off Ottawa's last spring frost of May 6.
Step 1 · Sow
Start seeds indoors
Apr 15 – May 6
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 6 – Sep 10
Picking runs until conditions turn against the crop.
Window
Days to maturity
85 – 120 d
Ottawa's 149-day season leaves this much room.
Winter squash / Pumpkin on Ottawa'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
HARVEST
MAY 6
OCT 2
Common questions
When can I sow winter squash / pumpkin outdoors in Ottawa?
Direct-sow around mid May (May 13–Jun 3) in Ottawa, based on its local frost dates. Confidence 84%.
When will winter squash / pumpkin be ready to harvest in Ottawa?
Expect to harvest from around early August (Aug 6–Sep 10) in Ottawa, based on its local frost dates. Confidence 76%.
When should I start winter squash / pumpkin seeds indoors in Ottawa?
Start seeds indoors around mid April (Apr 15–May 6) in Ottawa, based on its local frost dates. Confidence 80%.
When can I transplant winter squash / pumpkin outdoors in Ottawa?
Transplant outdoors around mid May (May 13–Jun 3) in Ottawa, based on its local frost dates. Confidence 84%.
How long is the growing season in Ottawa?
Ottawa has roughly 149 frost-free days, which is enough time to grow winter squash / pumpkin to maturity outdoors.
The rule of thumb
Sow winter squash / pumpkin 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 Ottawa's frost dates.
Confidence 84/100 · NOAA GHCN-Daily · 1991–2020 normals · frost dates are probabilities, not guarantees.