When to plant kale in Philadelphia

Kale is cold-hardy, so every date keys off Philadelphia's frost dates of Mar 28.
Step 1 · Sow
Start seeds indoors
Feb 14 – Mar 7
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Mar 7 – Mar 28
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 1 – May 21
Picking runs until conditions turn against the crop.
Step 4 · Second sowing
Autumn / second sowing
Aug 18 – Sep 1
A second window for a fall crop, timed to mature before the first frost.
Step 5 · Second harvest
Autumn crop harvest
Oct 19 – Nov 8
Maturity window for the second sowing.
Window
Days to maturity
55 – 75 d
Philadelphia's 234-day season leaves this much room.
Kale 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
MAR 28
NOV 22

Common questions

When can I sow kale outdoors in Philadelphia?

Direct-sow around early March (Mar 7–Mar 28) in Philadelphia, based on its local frost dates. Confidence 87%.

When will kale be ready to harvest in Philadelphia?

Expect to harvest from around early May (May 1–May 21) in Philadelphia, based on its local frost dates. Confidence 78%.

When should I start kale seeds indoors in Philadelphia?

Start seeds indoors around mid February (Feb 14–Mar 7) in Philadelphia, based on its local frost dates. Confidence 83%.

When can I transplant kale outdoors in Philadelphia?

Transplant outdoors around early March (Mar 7–Mar 28) in Philadelphia, based on its local frost dates. Confidence 87%.

Can I plant kale in autumn in Philadelphia?

Yes — Philadelphia supports a second, autumn sowing of kale around mid August (Aug 18–Sep 1), timed to mature before the first fall frost.

How long is the growing season in Philadelphia?

Philadelphia has roughly 234 frost-free days, which is enough time to grow kale to maturity outdoors.

The rule of thumb

Sow kale 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 Philadelphia's frost dates.

Confidence 87/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.