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When to Plant Horseradish in Ontario

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.

Ontario spans USDA hardiness zones 4a, 4b, 5b, 6a, 6b, 7a, 7b, 8a (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 Ontario

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 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
Zone 7a ~221 day growing season · Full guide →

Last frost: March 25 · First frost: November 1 · 221 day season

Activity When Date Range
Transplant Outdoors April 8 Apr 8 – Apr 22
Harvest August 12 Aug 12 – Oct 21
Zone 7b ~235 day growing season · Full guide →

Last frost: March 18 · First frost: November 8 · 235 day season

Activity When Date Range
Transplant Outdoors April 1 Apr 1 – Apr 15
Harvest August 5 Aug 5 – Oct 14
Zone 8a ~255 day growing season · Full guide →

Last frost: March 8 · First frost: November 18 · 255 day season

Activity When Date Range
Transplant Outdoors March 22 Mar 22 – Apr 5
Harvest July 26 Jul 26 – Oct 4

Growing Tips for Ontario

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 Ontario?

Planting dates for Horseradish in Ontario depend on your USDA zone. Ontario spans zones 4a, 4b, 5b, 6a, 6b, 7a, 7b, 8a. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Ontario for planting?

Ontario contains USDA hardiness zones 4a, 4b, 5b, 6a, 6b, 7a, 7b, 8a. 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.