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When to Plant Comfrey in Kittson 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.

Kittson County, Minnesota is in USDA Zone 3a. The average last spring frost is May 14 and the first fall frost is September 30, giving you a growing season of approximately 139 days.

At an elevation of 778 feet, Kittson County receives approximately 40.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78ยฐF, so choose short-season varieties of Comfrey to ensure they mature before fall.

Kittson County, MN (Zone 3a) Short season
139 days
Last Spring Frost May 14
139 growing days
First Fall Frost September 30

Kittson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Transplant: May 16 🍅 Harvest: Jul 18 – Sep 19
Recommended (50%) ✓ Fits season (6 days to spare)
Transplant: May 21 🍅 Harvest: Jul 23 – Sep 24
Safe Start (90%) ✓ Fits season (4 days to spare)
Transplant: Jun 6 🍅 Harvest: Aug 8 – Oct 10

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
1.2″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Comfrey needs ~638 GDD — county provides 1,181 GDD Excellent fit

Comfrey Planting Timeline โ€” Kittson County, MN

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 21 May 21 โ€“ Jun 4
Harvest July 23 Jul 23 โ€“ Sep 24

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 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 3a

Growing Season

139 days

Growing Tips for Kittson 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 Kittson County, MN?

Kittson County is in Zone 3a with an average last frost of May 14. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Kittson County, MN?

Kittson County, Minnesota is in USDA Hardiness Zone 3a. The average last spring frost is May 14 and first fall frost is September 30.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Kittson 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 Kittson County, MN. Local conditions may vary. Last updated: April 2026.