When to plant basil in Seattle
Basil is frost-tender, so every date keys off Seattle's last spring frost of Mar 17.
Step 1 · Sow
Start seeds indoors
Mar 9 – Mar 30
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 5 – Sep 4
Picking runs until conditions turn against the crop.
Window
Days to maturity
60 – 90 d
Seattle's 237-day season leaves this much room.
Basil 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 basil outdoors in Seattle?
Direct-sow around early June (Jun 6–Jun 27) in Seattle, based on its local frost dates. Confidence 81%.
When will basil be ready to harvest in Seattle?
Expect to harvest from around early August (Aug 5–Sep 4) in Seattle, based on its local frost dates. Confidence 75%.
When should I start basil seeds indoors in Seattle?
Start seeds indoors around early March (Mar 9–Mar 30) in Seattle, based on its local frost dates. Confidence 79%.
When can I transplant basil 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 basil to maturity outdoors.
The rule of thumb
Sow basil 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.