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When to Plant Comfrey in New Hampshire

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

New Hampshire spans USDA hardiness zones 4a, 4b, 5a, 5b (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.

Hover over a county to see details. Click to view planting guide.

Comfrey Planting Calendar for New Hampshire

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
Zone 5a ~166 day growing season · Full guide →

Last frost: April 25 · First frost: October 8 · 166 day season

Activity When Date Range
Transplant Outdoors May 2 May 2 – May 16
Harvest July 4 Jul 4 – Sep 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 April 25 Apr 25 – May 9
Harvest June 27 Jun 27 – Sep 5

Growing Tips for New Hampshire

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 New Hampshire?

Planting dates for Comfrey in New Hampshire depend on your USDA zone. New Hampshire spans zones 4a, 4b, 5a, 5b. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is New Hampshire for planting?

New Hampshire contains USDA hardiness zones 4a, 4b, 5a, 5b. 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.