When to plant lettuce in Denver

Lettuce 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 13 – May 4
Once frost risk has passed and nights stay mild.
Step 3 · Harvest
Harvest window
May 28 – Jun 12
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
Aug 27 – Sep 11
Maturity window for the second sowing.
Window
Days to maturity
45 – 60 d
Denver's 157-day season leaves this much room.
Lettuce 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 lettuce outdoors in Denver?

Direct-sow around early April (Apr 6–Apr 27) in Denver, based on its local frost dates. Confidence 85%.

When will lettuce be ready to harvest in Denver?

Expect to harvest from around late May (May 28–Jun 12) in Denver, based on its local frost dates. Confidence 76%.

When should I start lettuce 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 lettuce outdoors in Denver?

Transplant outdoors around mid April (Apr 13–May 4) in Denver, based on its local frost dates. Confidence 85%.

Can I plant lettuce in autumn in Denver?

Yes — Denver supports a second, autumn sowing of lettuce 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 lettuce to maturity outdoors.

The rule of thumb

Sow lettuce 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.