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When to Plant Corn in Idaho

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.

Idaho spans USDA hardiness zones 4a, 4b, 5a, 5b, 6a, 6b (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.

Find Your County

Click your county for exact Corn planting dates based on your local frost dates.

Corn Planting Calendar for Idaho

Zone 4a ~145 day growing season · Full guide →

Last frost: May 6 · First frost: September 28 · 145 day season

Activity When Date Range
Direct Sow May 20 May 20 – Jun 10
Harvest July 22 Jul 22 – Sep 16
Zone 4b ~155 day growing season · Full guide →

Last frost: May 1 · First frost: October 3 · 155 day season

Activity When Date Range
Direct Sow May 15 May 15 – Jun 5
Harvest July 17 Jul 17 – Sep 11
Zone 5a ~166 day growing season · Full guide →

Last frost: April 25 · First frost: October 8 · 166 day season

Activity When Date Range
Direct Sow May 2 May 2 – May 23
Harvest July 4 Jul 4 – Aug 29
Zone 5b ~178 day growing season · Full guide →

Last frost: April 18 · First frost: October 13 · 178 day season

Activity When Date Range
Direct Sow April 25 Apr 25 – May 16
Harvest June 27 Jun 27 – Aug 22
Zone 6a ~193 day growing season · Full guide →

Last frost: April 10 · First frost: October 20 · 193 day season

Activity When Date Range
Direct Sow April 17 Apr 17 – May 8
Harvest June 19 Jun 19 – Aug 14
Zone 6b ~205 day growing season · Full guide →

Last frost: April 3 · First frost: October 25 · 205 day season

Activity When Date Range
Direct Sow April 10 Apr 10 – May 1
Harvest June 12 Jun 12 – Aug 7

Growing Tips for Idaho

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.

Frequently Asked Questions

When should I plant Corn in Idaho?

Planting dates for Corn in Idaho depend on your USDA zone. Idaho spans zones 4a, 4b, 5a, 5b, 6a, 6b. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Idaho for planting?

Idaho contains USDA hardiness zones 4a, 4b, 5a, 5b, 6a, 6b. Your specific zone depends on your location within the state — northern and higher-elevation areas are in colder zones, while southern and coastal areas are warmer.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals, University Cooperative Extension planting guides. Last updated: April 2026.