Blog

When to Plant Radish in Ontario

Radishes are one of the fastest-growing vegetables, with some varieties ready in under a month. They come in round, elongated, and large winter types.

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 Radish planting dates based on your local frost dates.

Radish 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
Direct Sow April 29 Apr 29 – May 20
Harvest May 27 May 27 – Jun 17
Fall Sowing July 6 Jul 6 – Jul 20
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 April 24 Apr 24 – May 15
Harvest May 22 May 22 – Jun 12
Fall Sowing July 11 Jul 11 – Jul 25
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 4 Apr 4 – Apr 25
Harvest May 2 May 2 – May 23
Fall Sowing August 4 Aug 4 – Aug 18
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 March 27 Mar 27 – Apr 17
Harvest April 24 Apr 24 – May 15
Fall Sowing August 11 Aug 11 – Aug 25
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 March 20 Mar 20 – Apr 10
Harvest April 17 Apr 17 – May 8
Fall Sowing August 16 Aug 16 – Aug 30
Zone 7a ~221 day growing season · Full guide →

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

Activity When Date Range
Direct Sow March 11 Mar 11 – Apr 1
Harvest April 8 Apr 8 – Apr 29
Fall Sowing August 23 Aug 23 – Sep 6
Zone 7b ~235 day growing season · Full guide →

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

Activity When Date Range
Direct Sow March 4 Mar 4 – Mar 25
Harvest April 1 Apr 1 – Apr 22
Fall Sowing August 30 Aug 30 – Sep 13
Zone 8a ~255 day growing season · Full guide →

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

Activity When Date Range
Direct Sow February 22 Feb 22 – Mar 15
Harvest March 22 Mar 22 – Apr 12
Fall Sowing September 9 Sep 9 – Sep 23

Growing Tips for Ontario

Direct sow every 1-2 weeks for continuous harvest. Do not transplant. Harvest spring radishes promptly to prevent them from becoming pithy and hot.

Frequently Asked Questions

When should I plant Radish in Ontario?

Planting dates for Radish 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.