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When to Plant Comfrey in Northumberland County, PA

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

Northumberland County, Pennsylvania is in USDA Zone 6a. The average last spring frost is April 17 and the first fall frost is October 26, giving you a growing season of approximately 192 days.

At an elevation of 324 feet, Northumberland County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91ยฐF, providing good warmth for Comfrey during the growing season.

Northumberland County, PA (Zone 6a) Moderate season
192 days
Last Spring Frost April 17
192 growing days
First Fall Frost October 26

Northumberland County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (49 days to spare)
Transplant: Apr 20 🍅 Harvest: Jun 22 – Aug 31
Recommended (50%) ✓ Fits season (52 days to spare)
Transplant: Apr 24 🍅 Harvest: Jun 26 – Sep 4
Safe Start (90%) ✓ Fits season (44 days to spare)
Transplant: May 14 🍅 Harvest: Jul 16 – Sep 24

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 180 gal / 100 sq ft
Comfrey needs ~1,369 GDD — county provides 3,504 GDD Excellent fit

Comfrey Planting Timeline โ€” Northumberland County, PA

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 6a

Growing Season

192 days

Growing Tips for Northumberland 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 Northumberland County, PA?

Northumberland County is in Zone 6a 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 Northumberland County, PA?

Northumberland County, Pennsylvania is in USDA Hardiness Zone 6a. The average last spring frost is April 17 and first fall frost is October 26.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Northumberland County gardeners in Zone 6a 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 Northumberland County, PA. Local conditions may vary. Last updated: April 2026.