When to plant winter squash / pumpkin in Calgary
Winter squash / Pumpkin is frost-tender, so every date keys off Calgary's last spring frost of May 22.
Step 1 · Sow
Start seeds indoors
May 20 – Jun 10
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jul 18 – Aug 8
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Oct 11 – Nov 15
Picking runs until conditions turn against the crop.
Window
Days to maturity
85 – 120 d
Calgary's 120-day season leaves this much room.
Winter squash / Pumpkin on Calgary'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 22
SEP 19
Common questions
When can I sow winter squash / pumpkin outdoors in Calgary?
Direct-sow around mid July (Jul 18–Aug 8) in Calgary, based on its local frost dates. Confidence 80%.
When will winter squash / pumpkin be ready to harvest in Calgary?
Expect to harvest from around mid October (Oct 11–Nov 15) in Calgary, based on its local frost dates. Confidence 74%.
When should I start winter squash / pumpkin seeds indoors in Calgary?
Start seeds indoors around mid May (May 20–Jun 10) in Calgary, based on its local frost dates. Confidence 78%.
When can I transplant winter squash / pumpkin outdoors in Calgary?
Transplant outdoors around mid July (Jul 18–Aug 8) in Calgary, based on its local frost dates. Confidence 80%.
How long is the growing season in Calgary?
Calgary has roughly 120 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 Calgary's frost dates.
Confidence 82/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.