When to plant swiss chard in San Jose

Swiss chard is cold-hardy, so every date keys off San Jose's frost dates of Feb 12.
Step 1 · Sow
Start seeds indoors
Jan 15 – Feb 5
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Dec 25 – Jan 15
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Feb 13 – Feb 23
Picking runs until conditions turn against the crop.
Step 4 · Second sowing
Autumn / second sowing
Aug 28 – Sep 11
A second window for a fall crop, timed to mature before the first frost.
Step 5 · Second harvest
Autumn crop harvest
Oct 24 – Nov 3
Maturity window for the second sowing.
Window
Days to maturity
50 – 60 d
San Jose's 294-day season leaves this much room.
Swiss chard on San Jose'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
FEB 12
DEC 3

Common questions

When can I sow swiss chard outdoors in San Jose?

Direct-sow around late December (Dec 25–Jan 15) in San Jose, based on its local frost dates. Confidence 80%.

When will swiss chard be ready to harvest in San Jose?

Expect to harvest from around mid February (Feb 13–Feb 23) in San Jose, based on its local frost dates. Confidence 74%.

When should I start swiss chard seeds indoors in San Jose?

Start seeds indoors around mid January (Jan 15–Feb 5) in San Jose, based on its local frost dates. Confidence 78%.

When can I transplant swiss chard outdoors in San Jose?

Transplant outdoors around late December (Dec 25–Jan 15) in San Jose, based on its local frost dates. Confidence 80%.

Can I plant swiss chard in autumn in San Jose?

Yes — San Jose supports a second, autumn sowing of swiss chard around late August (Aug 28–Sep 11), timed to mature before the first fall frost.

How long is the growing season in San Jose?

San Jose has roughly 294 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 San Jose's frost dates.

Confidence 82/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.