Blog

When to Plant Comfrey in Minnesota

Comfrey is a vigorous perennial herb valued as a dynamic accumulator of nutrients. Its leaves make excellent mulch, compost activator, and liquid fertilizer.

Minnesota spans USDA hardiness zones 3a, 3b, 4a, 4b (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 Comfrey planting dates based on your local frost dates.

Comfrey Planting Calendar for Minnesota

Zone 3a ~123 day growing season · Full guide →

Last frost: May 15 · First frost: September 15 · 123 day season

Activity When Date Range
Transplant Outdoors May 22 May 22 – Jun 5
Harvest July 24 Jul 24 – Sep 25
Zone 3b ~135 day growing season · Full guide →

Last frost: May 10 · First frost: September 22 · 135 day season

Activity When Date Range
Transplant Outdoors May 17 May 17 – May 31
Harvest July 19 Jul 19 – Sep 20
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 May 13 May 13 – May 27
Harvest July 15 Jul 15 – Sep 23
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 8 May 8 – May 22
Harvest July 10 Jul 10 – Sep 18

Growing Tips for Minnesota

Plant root cuttings 2 inches deep. Choose Bocking 14 variety to prevent self-seeding. Cut leaves 3-4 times per season for mulch or compost. Avoid planting near pathways as it spreads.

Frequently Asked Questions

When should I plant Comfrey in Minnesota?

Planting dates for Comfrey in Minnesota depend on your USDA zone. Minnesota spans zones 3a, 3b, 4a, 4b. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Minnesota for planting?

Minnesota contains USDA hardiness zones 3a, 3b, 4a, 4b. 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.