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When to Plant Comfrey in Stevens 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.

Stevens County, Minnesota is in USDA Zone 4a. The average last spring frost is May 2 and the first fall frost is October 6, giving you a growing season of approximately 157 days.

At an elevation of 1,259 feet, Stevens County receives approximately 37.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Comfrey to ensure they mature before fall.

Stevens County, MN (Zone 4a) Moderate season
157 days
Last Spring Frost May 2
157 growing days
First Fall Frost October 6

Stevens County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (17 days to spare)
Transplant: May 3 🍅 Harvest: Jul 5 – Sep 13
Recommended (50%) ✓ Fits season (17 days to spare)
Transplant: May 9 🍅 Harvest: Jul 11 – Sep 19
Safe Start (90%) ✓ Fits season (15 days to spare)
Transplant: May 22 🍅 Harvest: Jul 24 – Oct 2

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
1.0″/week
Watering frequency Only during dry spells
Season total 4 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Comfrey needs ~806 GDD — county provides 1,687 GDD Excellent fit

Comfrey Planting Timeline โ€” Stevens County, MN

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 9 May 9 โ€“ May 23
Harvest July 11 Jul 11 โ€“ Sep 19

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 โ€”
July Harvest
August Harvest
September Harvest
October โ€”
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 4a

Growing Season

157 days

Growing Tips for Stevens 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 Stevens County, MN?

Stevens County is in Zone 4a with an average last frost of May 2. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Stevens County, MN?

Stevens County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 2 and first fall frost is October 6.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Stevens County gardeners in Zone 4a 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 Stevens County, MN. Local conditions may vary. Last updated: April 2026.