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When to Plant Mizuna in Ontario

Mizuna is a mild-flavored Japanese mustard green with feathery, deeply serrated leaves. It is fast-growing and makes an excellent addition to salads and stir-fries.

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 Mizuna planting dates based on your local frost dates.

Mizuna 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
Start Indoors March 25 Mar 25 – Apr 8
Transplant Outdoors May 6 May 6 – May 20
Direct Sow April 29 Apr 29 – May 20
Harvest June 10 Jun 10 – Jul 8
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
Start Indoors March 20 Mar 20 – Apr 3
Transplant Outdoors May 1 May 1 – May 15
Direct Sow April 24 Apr 24 – May 15
Harvest June 5 Jun 5 – Jul 3
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
Start Indoors March 14 Mar 14 – Mar 28
Transplant Outdoors April 18 Apr 18 – May 2
Direct Sow April 4 Apr 4 – Apr 25
Harvest May 23 May 23 – Jun 20
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
Start Indoors March 6 Mar 6 – Mar 20
Transplant Outdoors April 10 Apr 10 – Apr 24
Direct Sow March 27 Mar 27 – Apr 17
Harvest May 15 May 15 – Jun 12
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
Start Indoors February 27 Feb 27 – Mar 13
Transplant Outdoors April 3 Apr 3 – Apr 17
Direct Sow March 20 Mar 20 – Apr 10
Harvest May 8 May 8 – Jun 5
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
Start Indoors February 18 Feb 18 – Mar 4
Transplant Outdoors March 25 Mar 25 – Apr 8
Direct Sow March 11 Mar 11 – Apr 1
Harvest April 29 Apr 29 – May 27
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
Start Indoors February 11 Feb 11 – Feb 25
Transplant Outdoors March 18 Mar 18 – Apr 1
Direct Sow March 4 Mar 4 – Mar 25
Harvest April 22 Apr 22 – May 20
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
Start Indoors February 1 Feb 1 – Feb 15
Transplant Outdoors March 8 Mar 8 – Mar 22
Direct Sow February 22 Feb 22 – Mar 15
Harvest April 12 Apr 12 – May 10
Fall Sowing September 9 Sep 9 – Sep 23

Growing Tips for Ontario

Direct sow in spring or fall. Harvest outer leaves as needed for a cut-and-come-again approach. Mizuna is one of the most cold-tolerant Asian greens.

Frequently Asked Questions

When should I plant Mizuna in Ontario?

Planting dates for Mizuna 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.