When to plant summer squash / zucchini in Portland
Summer squash / Zucchini is frost-tender, so every date keys off Portland's last spring frost of May 1.
Step 1 · Sow
Start seeds indoors
Apr 27 – May 18
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jun 11 – Jul 2
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 26 – Aug 10
Picking runs until conditions turn against the crop.
Window
Days to maturity
45 – 60 d
Portland's 165-day season leaves this much room.
Summer squash / Zucchini on Portland'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 1
OCT 10
Common questions
When can I sow summer squash / zucchini outdoors in Portland?
Direct-sow around mid June (Jun 11–Jul 2) in Portland, based on its local frost dates. Confidence 86%.
When will summer squash / zucchini be ready to harvest in Portland?
Expect to harvest from around late July (Jul 26–Aug 10) in Portland, based on its local frost dates. Confidence 80%.
When should I start summer squash / zucchini seeds indoors in Portland?
Start seeds indoors around late April (Apr 27–May 18) in Portland, based on its local frost dates. Confidence 85%.
When can I transplant summer squash / zucchini outdoors in Portland?
Transplant outdoors around mid June (Jun 11–Jul 2) in Portland, based on its local frost dates. Confidence 86%.
How long is the growing season in Portland?
Portland has roughly 165 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 Portland's frost dates.
Confidence 89/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.