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When to Plant Garlic in Ontario

Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.

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 Garlic planting dates based on your local frost dates.

Garlic 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
Fall Sowing August 17 Aug 17 – Aug 31
Zone 4b ~155 day growing season · Full guide →

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

Activity When Date Range
Fall Sowing August 22 Aug 22 – Sep 5
Zone 5b ~178 day growing season · Full guide →

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

Activity When Date Range
Fall Sowing September 1 Sep 1 – Sep 15
Zone 6a ~193 day growing season · Full guide →

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

Activity When Date Range
Fall Sowing September 8 Sep 8 – Sep 22
Zone 6b ~205 day growing season · Full guide →

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

Activity When Date Range
Fall Sowing September 13 Sep 13 – Sep 27
Zone 7a ~221 day growing season · Full guide →

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

Activity When Date Range
Fall Sowing September 20 Sep 20 – Oct 4
Zone 7b ~235 day growing season · Full guide →

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

Activity When Date Range
Fall Sowing September 27 Sep 27 – Oct 11
Zone 8a ~255 day growing season · Full guide →

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

Activity When Date Range
Fall Sowing October 7 Oct 7 – Oct 21

Growing Tips for Ontario

Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.

Frequently Asked Questions

When should I plant Garlic in Ontario?

Planting dates for Garlic 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.