Blog

When to Plant Corn in Teton County, ID

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.

Teton County, Idaho is in USDA Zone 4b. The average last spring frost is May 31 and the first fall frost is September 11, giving you a growing season of approximately 103 days.

At an elevation of 6,709 feet, Teton County receives approximately 15.1 inches of rainfall annually with predominantly loam soil. Summer highs average 83ยฐF, 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.

Teton County, ID (Zone 4b) Short season
103 days
Last Spring Frost May 31
103 growing days
First Fall Frost September 11

Teton County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 21 🍅 Harvest: Jul 23 – Sep 17
Recommended (50%) ✗ May not fit
Transplant: May 31 🍅 Harvest: Aug 2 – Sep 27
Safe Start (90%) ✗ May not fit
Transplant: Jun 21 🍅 Harvest: Aug 23 – Oct 18

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
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 423 gal / 100 sq ft
Drought risk

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

Corn needs ~980 GDD — county provides 1,261 GDD Good fit

Corn Planting Timeline โ€” Teton County, ID

Corn Planting Calendar

Activity When Date Range
Direct Sow June 14 Jun 14 โ€“ Jul 5
Harvest August 16 Aug 16 โ€“ Oct 11

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May โ€”
June Direct Sow
July Direct Sow
August Harvest
September Harvest
October Harvest
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 4b

Growing Season

103 days

Growing Tips for Teton 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 Teton County, ID?

Teton County is in Zone 4b with an average last frost of May 31. Plan your Corn planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Teton County, ID?

Teton County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is May 31 and first fall frost is September 11.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Teton County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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