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When to Plant Cucumber in Custer County, CO

Cucumbers are a warm-season vine crop available in slicing and pickling varieties. They are prolific producers when given warmth, moisture, and a trellis to climb.

Custer County, Colorado is in USDA Zone 5a. The average last spring frost is May 23 and the first fall frost is September 25, giving you a growing season of approximately 125 days.

At an elevation of 8,115 feet, Custer County receives approximately 18.1 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Cucumber during the growing season. With low rainfall, drip irrigation is essential for growing Cucumber successfully. Mulch heavily to conserve soil moisture.

Custer County, CO (Zone 5a) Short season
125 days
Last Spring Frost May 23
125 growing days
First Fall Frost September 25

Custer County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (3 days to spare)
Start indoors: Apr 6 Transplant: May 25 🍅 Harvest: Jul 20 – Sep 14
Recommended (50%) ✗ May not fit
Start indoors: Apr 18 Transplant: Jun 6 🍅 Harvest: Aug 1 – Sep 26
Safe Start (90%) ✗ May not fit
Start indoors: May 11 Transplant: Jun 29 🍅 Harvest: Aug 24 – Oct 19

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.6″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 1,191 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Cucumber needs ~870 GDD — county provides 1,812 GDD Excellent fit

Cucumber Planting Timeline โ€” Custer County, CO

Cucumber Planting Calendar

Activity When Date Range
Start Indoors April 18 Apr 18 โ€“ May 2
Transplant Outdoors June 6 Jun 6 โ€“ Jun 20
Direct Sow May 30 May 30 โ€“ Jun 20
Harvest August 1 Aug 1 โ€“ Sep 26

Plant 0.5" deep ยท 24" apart ยท Rows 48" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow
July โ€”
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

50โ€“70 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

125 days

Growing Tips for Custer County

Direct sow after last frost or start indoors 3 weeks early. Provide a trellis for vining types to save space and improve air circulation. Harvest frequently to encourage production.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes
  • Sage

Level Up Your Garden

Frequently Asked Questions

When should I plant Cucumber in Custer County, CO?

Custer County is in Zone 5a with an average last frost of May 23. Plan your Cucumber planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Custer County, CO?

Custer County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is May 23 and first fall frost is September 25.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Custer County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Custer County, CO. Local conditions may vary. Last updated: April 2026.