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When to Plant Horseradish in Idaho

Horseradish is a vigorous perennial grown for its pungent, spicy roots used as a condiment. Once established, it can be difficult to eradicate, so choose its location carefully.

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 Horseradish planting dates based on your local frost dates.

Horseradish 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
Transplant Outdoors May 20 May 20 – Jun 3
Harvest September 23 Sep 23 – Oct 14
Zone 4b ~155 day growing season · Full guide →

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

Activity When Date Range
Transplant Outdoors May 15 May 15 – May 29
Harvest September 18 Sep 18 – Oct 9
Zone 5a ~166 day growing season · Full guide →

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

Activity When Date Range
Transplant Outdoors May 9 May 9 – May 23
Harvest September 12 Sep 12 – Oct 24
Zone 5b ~178 day growing season · Full guide →

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

Activity When Date Range
Transplant Outdoors May 2 May 2 – May 16
Harvest September 5 Sep 5 – Oct 17
Zone 6a ~193 day growing season · Full guide →

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

Activity When Date Range
Transplant Outdoors April 24 Apr 24 – May 8
Harvest August 28 Aug 28 – Nov 6
Zone 6b ~205 day growing season · Full guide →

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

Activity When Date Range
Transplant Outdoors April 17 Apr 17 – May 1
Harvest August 21 Aug 21 – Oct 30

Growing Tips for Idaho

Plant root cuttings at a 45-degree angle in early spring. Harvest roots in late fall for strongest flavor. Contain the plant with barriers or grow in large containers.

Frequently Asked Questions

When should I plant Horseradish in Idaho?

Planting dates for Horseradish 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.