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When to Plant Comfrey in Knox County, OH

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

Knox County, Ohio is in USDA Zone 6a. The average last spring frost is April 29 and the first fall frost is October 15, giving you a growing season of approximately 169 days.

At an elevation of 861 feet, Knox County receives approximately 33 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Comfrey during the growing season.

Knox County, OH (Zone 6a) Moderate season
169 days
Last Spring Frost April 29
169 growing days
First Fall Frost October 15

Knox County Soil Profile

Soil Type

Silt Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Comfrey Planting Timeline — Knox County, OH

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 6 May 6 – May 20
Harvest July 8 Jul 8 – Sep 16

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: N/A

🗺️ USDA Zone

Zone 6a

📆 Growing Season

169 days in Knox County

Growing Tips for Knox 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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Comfrey in Knox County, OH?

Knox County is in Zone 6a with an average last frost of April 29. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Knox County, OH?

Knox County, Ohio is in USDA Hardiness Zone 6a. The average last spring frost is April 29 and first fall frost is October 15.

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Your Knox County Garden Planner — Free

A 22-page printable planner built for Knox County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Knox County, OH. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.