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When to plant swiss chard in Denver

Swiss chard is cold-hardy, so every date keys off Denver's frost dates of May 4.
Step 1 · Sow
Start seeds indoors
Apr 6 – Apr 27
Before your last frost, on a warm windowsill or heat mat.
Step 2 · Plant
Transplant outdoors
Apr 20 – May 11
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
Jun 9 – Jun 19
Picking runs until conditions turn against the crop.
Step 4 · Second sowing
Autumn / second sowing
Jul 6 – Jul 20
A second window for a fall crop, timed to mature before the first frost.
Step 5 · Second harvest
Autumn crop harvest
Sep 1 – Sep 11
Maturity window for the second sowing.
Window
Days to maturity
50 – 60 d
Denver's 157-day season leaves this much room.
Swiss chard on Denver'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
MAY 4
OCT 10

Common questions

When can I sow swiss chard outdoors in Denver?

Direct-sow around mid April (Apr 20–May 11) in Denver, based on its local frost dates. Confidence 85%.

When will swiss chard be ready to harvest in Denver?

Expect to harvest from around early June (Jun 9–Jun 19) in Denver, based on its local frost dates. Confidence 76%.

When should I start swiss chard seeds indoors in Denver?

Start seeds indoors around early April (Apr 6–Apr 27) in Denver, based on its local frost dates. Confidence 81%.

When can I transplant swiss chard outdoors in Denver?

Transplant outdoors around mid April (Apr 20–May 11) in Denver, based on its local frost dates. Confidence 85%.

Can I plant swiss chard in autumn in Denver?

Yes — Denver supports a second, autumn sowing of swiss chard around early July (Jul 6–Jul 20), timed to mature before the first fall frost.

How long is the growing season in Denver?

Denver has roughly 157 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 Denver's frost dates.

Confidence 85/100 · Curated · based on NOAA GHCN-Daily 1991–2020 normal · frost dates are probabilities, not guarantees.
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