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When to Plant Comfrey in Blackford County, IN

Blackford County, Indiana Zone 6a May

Your May planting checklist for Blackford County, Indiana

May is a pivotal month for Blackford County, Indiana gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 26
Avg. first frost October 16
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.2 hrs
  1. Get comfrey in the ground

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

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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.

Blackford County, Indiana is in USDA Zone 6a. The average last spring frost is April 26 and the first fall frost is October 16, giving you a growing season of approximately 173 days.

At an elevation of 729 feet, Blackford County receives approximately 32.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Comfrey during the growing season.

Blackford County, IN (Zone 6a) Moderate season
173 days
Last Spring Frost April 26
173 growing days
First Fall Frost October 16
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Blackford County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (29 days to spare)
Transplant: Apr 29 🍅 Harvest: Jul 1 – Sep 9
Recommended (50%) ✓ Fits season (33 days to spare)
Transplant: May 3 🍅 Harvest: Jul 5 – Sep 13
Safe Start (90%) ✓ Fits season (27 days to spare)
Transplant: May 19 🍅 Harvest: Jul 21 – Sep 29

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 Blackford County

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

Soil pH

Your soil pH (6.0–7.0) is within Comfrey's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.8%) — Comfrey will thrive.

How to Plant Comfrey

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

Succession Planting Comfrey

3
successive plantings in your 173-day season

Sow every 6.9 weeks. Last sowing by Jul 18 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 317 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 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 3.2" 1.1" 💧 Light watering
Aug 4.3" 3.1" 1.2" 💧 Light watering
Sep 4.3" 2.5" 1.8" 💧 Light watering
Oct 4.3" 2.8" 1.5" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Blackford 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 2,638 GDD Excellent fit

Comfrey Planting Timeline — Blackford County, IN

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 3 May 3 – May 17
Harvest July 5 Jul 5 – Sep 13

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
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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: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

173 days in Blackford County

Growing Tips for Comfrey in Blackford County

Direct sow Comfrey outdoors after April 26 in Blackford 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 Blackford County, IN?

Blackford County is in Zone 6a with an average last frost of April 26. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Blackford County, IN?

Blackford County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 26 and first fall frost is October 16.

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Your Blackford County Garden Planner — Free

A 24-page printable planner built for Blackford 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 Blackford County, IN. 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.