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When to Plant Comfrey in Linn County, MO

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

Linn County, Missouri is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 20, giving you a growing season of approximately 186 days.

At an elevation of 880 feet, Linn County receives approximately 32.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Comfrey during the growing season.

Linn County, MO (Zone 5b) Moderate season
186 days
Last Spring Frost April 17
186 growing days
First Fall Frost October 20

Linn County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Transplant: Apr 18 🍅 Harvest: Jun 20 – Aug 29
Recommended (50%) ✓ Fits season (46 days to spare)
Transplant: Apr 24 🍅 Harvest: Jun 26 – Sep 4
Safe Start (90%) ✓ Fits season (45 days to spare)
Transplant: May 7 🍅 Harvest: Jul 9 – Sep 17

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
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 533 gal / 100 sq ft
Drought risk

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

Comfrey needs ~1,031 GDD — county provides 2,557 GDD Excellent fit

Comfrey Planting Timeline โ€” Linn County, MO

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors April 24 Apr 24 โ€“ May 8
Harvest June 26 Jun 26 โ€“ Sep 4

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May Transplant Outdoors
June Harvest
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 5b

Growing Season

186 days

Growing Tips for Linn 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 Linn County, MO?

Linn County is in Zone 5b with an average last frost of April 17. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Linn County, MO?

Linn County, Missouri is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 20.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Linn County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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Free download. Plan your entire garden season in minutes.

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