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When to Plant Squash (Winter) in Ontario

Winter squash includes butternut, acorn, delicata, and hubbard varieties grown to full maturity with hard rinds for storage. They develop sweet, dense flesh.

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 Squash (Winter) planting dates based on your local frost dates.

Squash (Winter) 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 27 May 27 – Jun 10
Direct Sow May 20 May 20 – Jun 10
Harvest August 19 Aug 19 – 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
Start Indoors March 20 Mar 20 – Apr 3
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 15 May 15 – Jun 5
Harvest August 14 Aug 14 – 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
Start Indoors March 14 Mar 14 – Mar 28
Transplant Outdoors May 2 May 2 – May 16
Direct Sow April 25 Apr 25 – May 16
Harvest July 25 Jul 25 – Sep 19
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 24 Apr 24 – May 8
Direct Sow April 17 Apr 17 – May 8
Harvest July 17 Jul 17 – Sep 11
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 17 Apr 17 – May 1
Direct Sow April 10 Apr 10 – May 1
Harvest July 10 Jul 10 – Sep 4
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 25 Feb 25 – Mar 11
Transplant Outdoors April 8 Apr 8 – Apr 22
Direct Sow April 1 Apr 1 – Apr 22
Harvest July 1 Jul 1 – Aug 26
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 18 Feb 18 – Mar 4
Transplant Outdoors April 1 Apr 1 – Apr 15
Direct Sow March 25 Mar 25 – Apr 15
Harvest June 24 Jun 24 – Aug 19
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 8 Feb 8 – Feb 22
Transplant Outdoors March 22 Mar 22 – Apr 5
Direct Sow March 15 Mar 15 – Apr 5
Harvest June 14 Jun 14 – Aug 9

Growing Tips for Ontario

Direct sow after last frost on rich mounds. Allow ample space for sprawling vines. Cure harvested fruits in the sun for 10 days before storing in a cool, dry place.

Frequently Asked Questions

When should I plant Squash (Winter) in Ontario?

Planting dates for Squash (Winter) 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.