When to plant swiss chard in Philadelphia

Swiss chard is cold-hardy, so every date keys off Philadelphia's frost dates of Mar 28.
Step 1 · Sow
Start seeds indoors
Feb 28 – Mar 21
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Mar 23 – Apr 13
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 12 – May 22
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 14 – Oct 24
Maturity window for the second sowing.
Window
Days to maturity
50 – 60 d
Philadelphia's 234-day season leaves this much room.
Swiss chard 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 swiss chard outdoors in Philadelphia?

Direct-sow around late March (Mar 23–Apr 13) in Philadelphia, based on its local frost dates. Confidence 84%.

When will swiss chard be ready to harvest in Philadelphia?

Expect to harvest from around mid May (May 12–May 22) in Philadelphia, based on its local frost dates. Confidence 78%.

When should I start swiss chard seeds indoors in Philadelphia?

Start seeds indoors around late February (Feb 28–Mar 21) in Philadelphia, based on its local frost dates. Confidence 83%.

When can I transplant swiss chard outdoors in Philadelphia?

Transplant outdoors around late March (Mar 23–Apr 13) in Philadelphia, based on its local frost dates. Confidence 84%.

Can I plant swiss chard in autumn in Philadelphia?

Yes — Philadelphia supports a second, autumn sowing of swiss chard 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 swiss chard to maturity outdoors.

The rule of thumb

Sow swiss chard 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.