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 Mar 1.
Step 1 · Sow
Start seeds indoors
Mar 3 – Mar 24
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jun 5 – Jun 26
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jul 20 – Aug 4
Picking runs until conditions turn against the crop.
Window
Days to maturity
45 – 60 d
Portland's 266-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
MAR 1
NOV 22
Common questions
When can I sow summer squash / zucchini outdoors in Portland?
Direct-sow around early June (Jun 5–Jun 26) in Portland, based on its local frost dates. Confidence 85%.
When will summer squash / zucchini be ready to harvest in Portland?
Expect to harvest from around mid July (Jul 20–Aug 4) in Portland, based on its local frost dates. Confidence 79%.
When should I start summer squash / zucchini seeds indoors in Portland?
Start seeds indoors around early March (Mar 3–Mar 24) in Portland, based on its local frost dates. Confidence 84%.
When can I transplant summer squash / zucchini outdoors in Portland?
Transplant outdoors around early June (Jun 5–Jun 26) in Portland, based on its local frost dates. Confidence 85%.
How long is the growing season in Portland?
Portland has roughly 266 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 88/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.