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When to Plant Comfrey in Koochiching County, MN

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

Koochiching County, Minnesota is in USDA Zone 3a. The average last spring frost is May 22 and the first fall frost is September 18, giving you a growing season of approximately 119 days.

At an elevation of 508 feet, Koochiching County receives approximately 41.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79ยฐF, so choose short-season varieties of Comfrey to ensure they mature before fall.

Koochiching County, MN (Zone 3a) Short season
119 days
Last Spring Frost May 22
119 growing days
First Fall Frost September 18

Koochiching County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 23 🍅 Harvest: Jul 25 – Sep 26
Recommended (50%) ✗ May not fit
Transplant: May 29 🍅 Harvest: Jul 31 – Oct 2
Safe Start (90%) ✗ May not fit
Transplant: Jun 22 🍅 Harvest: Aug 24 – Oct 26

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Comfrey needs ~694 GDD — county provides 1,100 GDD Excellent fit

Comfrey Planting Timeline โ€” Koochiching County, MN

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 29 May 29 โ€“ Jun 12
Harvest July 31 Jul 31 โ€“ Oct 2

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Transplant Outdoors
June Transplant Outdoors
July Harvest
August Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 3a

Growing Season

119 days

Growing Tips for Koochiching County

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.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Comfrey in Koochiching County, MN?

Koochiching County is in Zone 3a with an average last frost of May 22. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Koochiching County, MN?

Koochiching County, Minnesota is in USDA Hardiness Zone 3a. The average last spring frost is May 22 and first fall frost is September 18.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Koochiching County gardeners in Zone 3a organize planting dates, track what's growing, and never miss a planting window.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Koochiching County, MN. Local conditions may vary. Last updated: April 2026.