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When to Plant Corn in Toole County, MT

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.

Toole County, Montana is in USDA Zone 4a. The average last spring frost is May 24 and the first fall frost is September 17, giving you a growing season of approximately 116 days.

At an elevation of 7,194 feet, Toole County receives approximately 23.3 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.

Toole County, MT (Zone 4a) Short season
116 days
Last Spring Frost May 24
116 growing days
First Fall Frost September 17

Toole County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 18 🍅 Harvest: Jul 20 – Sep 14
Recommended (50%) ✗ May not fit
Transplant: May 24 🍅 Harvest: Jul 26 – Sep 20
Safe Start (90%) ✗ May not fit
Transplant: Jun 14 🍅 Harvest: Aug 16 – Oct 11

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
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 194 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 1,421 GDD Excellent fit

Corn Planting Timeline โ€” Toole County, MT

Corn Planting Calendar

Activity When Date Range
Direct Sow June 7 Jun 7 โ€“ Jun 28
Harvest August 9 Aug 9 โ€“ Oct 4

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 โ€”
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 4a

Growing Season

116 days

Growing Tips for Toole 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 Toole County, MT?

Toole County is in Zone 4a with an average last frost of May 24. Plan your Corn planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Toole County, MT?

Toole County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 24 and first fall frost is September 17.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Toole 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 Toole County, MT. Local conditions may vary. Last updated: April 2026.