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When to Plant Cucumber in Yellowstone County, MT

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.

Yellowstone County, Montana is in USDA Zone 4b. The average last spring frost is May 9 and the first fall frost is October 3, giving you a growing season of approximately 147 days.

At an elevation of 7,432 feet, Yellowstone County receives approximately 21.1 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Cucumber to ensure they mature before fall.

Yellowstone County, MT (Zone 4b) Short season
147 days
Last Spring Frost May 9
147 growing days
First Fall Frost October 3

Yellowstone County Soil Profile

Soil Type

Loam

Soil pH

6.2-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (8 days to spare)
Start indoors: Mar 23 Transplant: May 25 🍅 Harvest: Jul 20 – Sep 14
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Mar 28 Transplant: May 30 🍅 Harvest: Jul 25 – Sep 19
Safe Start (90%) ✓ Fits season (16 days to spare)
Start indoors: Apr 10 Transplant: Jun 12 🍅 Harvest: Aug 7 – Oct 2

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
1.6″/week
Watering frequency 2-3 times/week
Season total 2,115 gal / 100 sq ft
Drought risk

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

Cucumber needs ~600 GDD — county provides 1,470 GDD Excellent fit

Cucumber Planting Timeline โ€” Yellowstone County, MT

Cucumber Planting Calendar

Activity When Date Range
Start Indoors March 28 Mar 28 โ€“ Apr 11
Transplant Outdoors May 30 May 30 โ€“ Jun 13
Direct Sow May 23 May 23 โ€“ Jun 13
Harvest July 25 Jul 25 โ€“ Sep 19

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Harvest
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 4b

Growing Season

147 days

Growing Tips for Yellowstone 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 Yellowstone County, MT?

Yellowstone County is in Zone 4b with an average last frost of May 9. Plan your Cucumber planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Yellowstone County, MT?

Yellowstone County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 9 and first fall frost is October 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Yellowstone County gardeners in Zone 4b 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 Yellowstone County, MT. Local conditions may vary. Last updated: April 2026.