When to plant broccoli in Seattle

Broccoli is cold-hardy, so every date keys off Seattle's frost dates of Mar 17.
Step 1 · Sow
Start seeds indoors
Feb 3 – Feb 24
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Dec 26 – Jan 16
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Feb 24 – Mar 21
Picking runs until conditions turn against the crop.
Step 4 · Second sowing
Autumn / second sowing
Jul 30 – Aug 13
A second window for a fall crop, timed to mature before the first frost.
Step 5 · Second harvest
Autumn crop harvest
Oct 5 – Oct 30
Maturity window for the second sowing.
Window
Days to maturity
60 – 85 d
Seattle's 237-day season leaves this much room.
Broccoli 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
MAR 17
NOV 13

Common questions

When will broccoli be ready to harvest in Seattle?

Expect to harvest from around late February (Feb 24–Mar 21) in Seattle, based on its local frost dates. Confidence 75%.

When should I start broccoli seeds indoors in Seattle?

Start seeds indoors around early February (Feb 3–Feb 24) in Seattle, based on its local frost dates. Confidence 79%.

When can I transplant broccoli outdoors in Seattle?

Transplant outdoors around late December (Dec 26–Jan 16) in Seattle, based on its local frost dates. Confidence 81%.

Can I plant broccoli in autumn in Seattle?

Yes — Seattle supports a second, autumn sowing of broccoli around late July (Jul 30–Aug 13), 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 broccoli to maturity outdoors.

The rule of thumb

Sow broccoli 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.