When to plant winter squash / pumpkin in Seattle
Winter squash / Pumpkin is frost-tender, so every date keys off Seattle's last spring frost of Mar 17.
Step 1 · Sow
Start seeds indoors
Mar 23 – Apr 13
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Jun 6 – Jun 27
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Aug 30 – Oct 4
Picking runs until conditions turn against the crop.
Window
Days to maturity
85 – 120 d
Seattle's 237-day season leaves this much room.
Winter squash / Pumpkin on Seattle'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
MAR 17
NOV 13
Common questions
When can I sow winter squash / pumpkin outdoors in Seattle?
Direct-sow around early June (Jun 6–Jun 27) in Seattle, based on its local frost dates. Confidence 81%.
When will winter squash / pumpkin be ready to harvest in Seattle?
Expect to harvest from around late August (Aug 30–Oct 4) in Seattle, based on its local frost dates. Confidence 75%.
When should I start winter squash / pumpkin seeds indoors in Seattle?
Start seeds indoors around late March (Mar 23–Apr 13) in Seattle, based on its local frost dates. Confidence 79%.
When can I transplant winter squash / pumpkin outdoors in Seattle?
Transplant outdoors around early June (Jun 6–Jun 27) in Seattle, based on its local frost dates. Confidence 81%.
How long is the growing season in Seattle?
Seattle has roughly 237 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 Seattle's frost dates.
Confidence 83/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.