When to plant basil in Philadelphia
Basil is frost-tender, so every date keys off Philadelphia's last spring frost of Mar 28.
Step 1 · Sow
Start seeds indoors
Mar 6 – Mar 27
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 30 – May 21
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 29 – Jul 29
Picking runs until conditions turn against the crop.
Window
Days to maturity
60 – 90 d
Philadelphia's 234-day season leaves this much room.
Basil on Philadelphia'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 28
NOV 22
Common questions
When can I sow basil outdoors in Philadelphia?
Direct-sow around late April (Apr 30–May 21) in Philadelphia, based on its local frost dates. Confidence 84%.
When will basil be ready to harvest in Philadelphia?
Expect to harvest from around late June (Jun 29–Jul 29) in Philadelphia, based on its local frost dates. Confidence 78%.
When should I start basil seeds indoors in Philadelphia?
Start seeds indoors around early March (Mar 6–Mar 27) in Philadelphia, based on its local frost dates. Confidence 83%.
When can I transplant basil outdoors in Philadelphia?
Transplant outdoors around late April (Apr 30–May 21) in Philadelphia, based on its local frost dates. Confidence 84%.
How long is the growing season in Philadelphia?
Philadelphia has roughly 234 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 Philadelphia's frost dates.
Confidence 87/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.