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When to Plant Comfrey in Carroll County, MD

Carroll County, Maryland Zone 7a May

Top priorities for Carroll County, Maryland gardeners in May

Your garden in Carroll County, Maryland is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost April 17
Avg. first frost October 26
Soil temp (4") 63°F
Watering Low
Pest pressure Low
Daylight 14.2 hrs
Get ahead of June
  • First harvests: comfrey

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

Carroll County, Maryland is in USDA Zone 7a. 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 715 feet, Carroll County receives approximately 42.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Comfrey during the growing season.

Carroll County, MD (Zone 7a) Moderate season
192 days
Last Spring Frost April 17
192 growing days
First Fall Frost October 26
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Carroll County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (48 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 (41 days to spare)
Transplant: May 16 🍅 Harvest: Jul 18 – Sep 26

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.

Soil Compatibility in Carroll County

How your county's soil matches Comfrey's growing requirements.

Soil pH

Your soil pH (5.6–6.5) overlaps with Comfrey's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Carroll County is excellent for Comfrey — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Comfrey.

How to Plant Comfrey

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Comfrey

3
successive plantings in your 192-day season

Sow every 6.9 weeks. Last sowing by Jul 28 to harvest before frost.

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 135 gal / 100 sq ft

Monthly Watering Guide for Comfrey

Comfrey needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Comfrey Needs Rainfall You Supplement Action
Jan 3.2" 0" ❄️ Dormant
Feb 2.7" 0" ❄️ Dormant
Mar 3.3" 0" ❄️ Dormant
Apr 4.3" 3.9" 0.4" 💧 Light watering
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 3.7" 0.6" 💧 Light watering
Jul 4.3" 4.6" 0" ✅ Rainfall sufficient
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 3.4" 0" ❄️ Dormant
Dec 3.5" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Carroll County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Comfrey Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Comfrey needs ~1,144 GDD — county provides 2,928 GDD Excellent fit

Comfrey Planting Timeline — Carroll County, MD

Comfrey Planting Calendar

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

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 7a

📆 Growing Season

192 days in Carroll County

Growing Tips for Comfrey in Carroll County

Direct sow Comfrey outdoors after April 17 in Carroll County when soil has warmed and frost danger has passed.

General growing tips

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 Carroll County, MD?

Carroll County is in Zone 7a with an average last frost of April 17. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Carroll County, MD?

Carroll County, Maryland is in USDA Hardiness Zone 7a. The average last spring frost is April 17 and first fall frost is October 26.

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Your Carroll County Garden Planner — Free

A 24-page printable planner built for Carroll County (Zone 7a). 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 Carroll County, MD. Local conditions may vary. Last updated: May 2026.

Sources & credits

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