Colorado · zones 5a–7a
When to plant cucumbers in Colorado.
Sow between May 16 to Jul 13 in a typical year, keyed to Colorado's median last frost around May 9. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Cucumbers dates for a typical Colorado season.
Direct sow
May 16 to Jul 13
Keyed to the ~May 9 last frost. Sow 1" deep, 12" apart.
Harvest
~60 days later
~5 lb per plant over ~5 weeks.
Colorado spans more than one climate: Zone 6 is the most common zone, but the state runs 5a to 7a. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
In Colorado: watch for
The pests that find cucumbers here.
The short season here, about 143 frost-free days, keeps cucumber, slicing in front of squash bugs only briefly. One early row cover usually carries a planting through the worst of it.
Gray shield bugs; leaves wilt and get crispy patches.
Organic fix: Crush the copper egg rows under leaves; diatomaceous earth at the base.
Yellow striped or spotted beetles that spread bacterial wilt.
Organic fix: Row cover until the first female flowers open; neem for heavy runs.
Angular yellow patches bounded by the leaf veins, after wet foliage.
Organic fix: Water in the morning, space for airflow, pull badly infected vines.
White powder coating the leaves late in the season.
Organic fix: Space for airflow, water at the base, spray neem.
Your season math: Colorado gives cucumbers about 143 frost-free days, and it needs roughly 60 days to a first harvest. That fits about 4 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting cucumbers in Colorado: questions
When should I plant cucumbers in Colorado?+
In a typical Colorado year, sow cucumbers between May 16 to Jul 13, keyed to the state's median last frost around May 9. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Colorado?+
Colorado spans zones 5a–7a, mostly zone 6. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many cucumbers plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.