When to plant leek in Denver
Leek is cold-hardy, so every date keys off Denver's frost dates of May 4.
Step 1 · Sow
Start seeds indoors
Feb 23 – Mar 16
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
Jul 29 – Aug 18
Picking runs until conditions turn against the crop.
Window
Days to maturity
100 – 120 d
Denver's 157-day season leaves this much room.
Leek 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
FROST
FROST
MAY 4
OCT 10
Common questions
When will leek be ready to harvest in Denver?
Expect to harvest from around late July (Jul 29–Aug 18) in Denver, based on its local frost dates. Confidence 76%.
When should I start leek seeds indoors in Denver?
Start seeds indoors around late February (Feb 23–Mar 16) in Denver, based on its local frost dates. Confidence 81%.
When can I transplant leek outdoors in Denver?
Transplant outdoors around mid April (Apr 20–May 11) in Denver, based on its local frost dates. Confidence 85%.
How long is the growing season in Denver?
Denver has roughly 157 frost-free days, which is enough time to grow leek to maturity outdoors.
The rule of thumb
Sow leek 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.