When to plant spinach in Seattle
Spinach is cold-hardy, so every date keys off Seattle's frost dates of Mar 17.
Step 1 · Sow
Direct sow outdoors
Dec 26 – Jan 16
Sow straight into warm, workable soil.
Step 2 · Harvest
Harvest window
Feb 4 – Feb 14
Picking runs until conditions turn against the crop.
Step 3 · Second sowing
Autumn / second sowing
Sep 3 – Sep 17
A second window for a fall crop, timed to mature before the first frost.
Step 4 · Second harvest
Autumn crop harvest
Oct 20 – Oct 30
Maturity window for the second sowing.
Window
Days to maturity
40 – 50 d
Seattle's 237-day season leaves this much room.
Spinach 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
MAR 17
NOV 13
Common questions
When can I sow spinach outdoors in Seattle?
Direct-sow around late December (Dec 26–Jan 16) in Seattle, based on its local frost dates. Confidence 81%.
When will spinach be ready to harvest in Seattle?
Expect to harvest from around early February (Feb 4–Feb 14) in Seattle, based on its local frost dates. Confidence 75%.
Can I plant spinach in autumn in Seattle?
Yes — Seattle supports a second, autumn sowing of spinach around early September (Sep 3–Sep 17), timed to mature before the first fall frost.
How long is the growing season in Seattle?
Seattle has roughly 237 frost-free days, which is enough time to grow spinach to maturity outdoors.
The rule of thumb
Sow spinach as soon as the soil is workable — it tolerates cool weather and light frost. 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.