When to Plant Rhubarb in Ontario
Rhubarb is a long-lived perennial vegetable grown for its tart, colorful stalks. Only the stalks are edible as the leaves contain toxic oxalic acid.
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 Rhubarb planting dates based on your local frost dates.
Rhubarb 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 | June 3 | Jun 3 – Jun 17 |
▸ 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 29 | May 29 – Jun 12 |
▸ 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 9 | May 9 – May 23 |
▸ 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 | May 1 | May 1 – May 15 |
▸ 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 24 | Apr 24 – May 8 |
▸ 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 15 | Apr 15 – Apr 29 |
▸ 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 8 | Apr 8 – Apr 22 |
▸ 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 29 | Mar 29 – Apr 12 |
Growing Tips for Ontario
Plant crowns in early spring in rich, well-drained soil. Do not harvest stalks the first year. Pull (do not cut) stalks at harvest to avoid introducing rot.
Rhubarb in Other States
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Rhubarb in Ontario?
Planting dates for Rhubarb 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.