When to plant summer squash / zucchini in Ottawa
Summer squash / Zucchini is frost-tender, so every date keys off Ottawa's last spring frost of May 6.
Step 1 · Sow
Start seeds indoors
Apr 22 – May 13
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
Jun 27 – Jul 12
Picking runs until conditions turn against the crop.
Window
Days to maturity
45 – 60 d
Ottawa's 149-day season leaves this much room.
Summer squash / Zucchini 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
MAY 6
OCT 2
Common questions
When can I sow summer squash / zucchini outdoors in Ottawa?
Direct-sow around mid May (May 13–Jun 3) in Ottawa, based on its local frost dates. Confidence 84%.
When will summer squash / zucchini be ready to harvest in Ottawa?
Expect to harvest from around late June (Jun 27–Jul 12) in Ottawa, based on its local frost dates. Confidence 76%.
When should I start summer squash / zucchini seeds indoors in Ottawa?
Start seeds indoors around late April (Apr 22–May 13) in Ottawa, based on its local frost dates. Confidence 80%.
When can I transplant summer squash / zucchini 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 summer squash / zucchini to maturity outdoors.
The rule of thumb
Sow summer squash / zucchini 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.