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When to Plant Comfrey in Harrison 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.

Harrison County, Missouri is in USDA Zone 5b. The average last spring frost is April 19 and the first fall frost is October 15, giving you a growing season of approximately 179 days.

At an elevation of 1,349 feet, Harrison County receives approximately 37.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Comfrey to ensure they mature before fall.

Harrison County, MO (Zone 5b) Moderate season
179 days
Last Spring Frost April 19
179 growing days
First Fall Frost October 15

Harrison County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (39 days to spare)
Transplant: Apr 20 🍅 Harvest: Jun 22 – Aug 31
Recommended (50%) ✓ Fits season (39 days to spare)
Transplant: Apr 26 🍅 Harvest: Jun 28 – Sep 6
Safe Start (90%) ✓ Fits season (41 days to spare)
Transplant: May 10 🍅 Harvest: Jul 12 – Sep 20

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
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 184 gal / 100 sq ft
Comfrey needs ~975 GDD — county provides 2,327 GDD Excellent fit

Comfrey Planting Timeline โ€” Harrison County, MO

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors April 26 Apr 26 โ€“ May 10
Harvest June 28 Jun 28 โ€“ Sep 6

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

179 days

Growing Tips for Harrison 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 Harrison County, MO?

Harrison County is in Zone 5b with an average last frost of April 19. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Harrison County, MO?

Harrison County, Missouri is in USDA Hardiness Zone 5b. The average last spring frost is April 19 and first fall frost is October 15.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Harrison County gardeners in Zone 5b 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 Harrison County, MO. Local conditions may vary. Last updated: April 2026.