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When to Plant Corn in Fremont County, WY

Corn is a warm-season grass grown for its sweet ears, which are best eaten soon after harvest. It is wind-pollinated and must be planted in blocks for good kernel fill.

Fremont County, Wyoming is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 21, giving you a growing season of approximately 129 days.

At an elevation of 6,059 feet, Fremont County receives approximately 14.8 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Corn to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Corn successfully. Mulch heavily to conserve soil moisture.

Fremont County, WY (Zone 4a) Short season
129 days
Last Spring Frost May 15
129 growing days
First Fall Frost September 21

Fremont County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (10 days to spare)
Transplant: May 11 🍅 Harvest: Jul 13 – Sep 7
Recommended (50%) ✓ Fits season (10 days to spare)
Transplant: May 15 🍅 Harvest: Jul 17 – Sep 11
Safe Start (90%) ✓ Fits season (1 days to spare)
Transplant: Jun 10 🍅 Harvest: Aug 12 – Oct 7

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
1.0″/week
Rainfall provides
0.5″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,127 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Corn needs ~800 GDD — county provides 1,290 GDD Excellent fit

Corn Planting Timeline โ€” Fremont County, WY

Corn Planting Calendar

Activity When Date Range
Direct Sow May 29 May 29 โ€“ Jun 19
Harvest July 31 Jul 31 โ€“ Sep 25

Plant 1" deep ยท 12" apart ยท Rows 36" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“100 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

129 days

Growing Tips for Fremont County

Plant in blocks of at least 4 rows rather than single rows for proper pollination. Direct sow after soil reaches 60F. Side-dress with nitrogen when plants are knee-high.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Celery

Level Up Your Garden

Frequently Asked Questions

When should I plant Corn in Fremont County, WY?

Fremont County is in Zone 4a with an average last frost of May 15. Plan your Corn planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Fremont County, WY?

Fremont County, Wyoming is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 21.

๐ŸŒฑ

Plan Your Garden with Confidence

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