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When to plant Comfrey in Penobscot County, ME

Plant Comfrey in Penobscot County, between May 17 and May 31 — the only viable window. Zone 5a's short season (145 frost-free days) rules out a fall crop.

When to Plant Comfrey in Penobscot County, ME

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

Penobscot County, Maine is in USDA Zone 5a. The average last spring frost is May 10 and the first fall frost is October 2, giving you a growing season of approximately 145 days.

At an elevation of 842 feet, Penobscot County receives approximately 38.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Comfrey to ensure they mature before fall.

Penobscot County, ME (Zone 5a) Short season
145 days
Last Spring Frost May 10
145 growing days
First Fall Frost October 2

Penobscot County Soil Profile

Soil Type

Silt Loam

Soil pH

6.0-7.0

Drainage

Well Drained

Comfrey Planting Timeline — Penobscot County, ME

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 17 May 17 – May 31
Harvest July 19 Jul 19 – Sep 27

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 5a

📆 Growing Season

145 days in Penobscot County

Growing Tips for Penobscot 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 Penobscot County, ME?

Penobscot County is in Zone 5a with an average last frost of May 10. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Penobscot County, ME?

Penobscot County, Maine is in USDA Hardiness Zone 5a. The average last spring frost is May 10 and first fall frost is October 2.

When should I plant Comfrey in Penobscot County, ME?

In Penobscot County, ME, plant Comfrey after the last frost (around May 10) and before the first frost (around October 2). Best results when soil holds above 50°F.

What growing zone is Penobscot County, ME for Comfrey?

Penobscot County sits in USDA Zone 5a. Comfrey grows reliably in zones 3a through 9b, so it's a good fit here.

Can Comfrey grow in Penobscot County's climate?

Yes — Comfrey grows well in Penobscot County's temperate climate. Penobscot County averages a 145-day frost-free season, with last frost around May 10 and first frost around October 2.

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Your Penobscot County Garden Planner — Free

A 22-page printable planner built for Penobscot County (Zone 5a). 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 Penobscot County, ME. Local conditions may vary. Last updated: June 2026.

Sources & credits

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