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When to Plant Comfrey in Barnwell County, SC

Barnwell County, South Carolina Zone 8b May

Your May planting checklist for Barnwell County, South Carolina

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Barnwell County, South Carolina.

Avg. last frost March 22
Avg. first frost November 10
Soil temp (4") 72°F
Watering Moderate
Pest pressure High
Daylight 13.7 hrs
  1. Bring in the comfrey

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

June will be here before you know it — start on
  • 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.

Barnwell County, South Carolina is in USDA Zone 8b. The average last spring frost is March 22 and the first fall frost is November 10, giving you a growing season of approximately 233 days.

At an elevation of 157 feet, Barnwell County receives approximately 48.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 97°F, so Comfrey may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Comfrey will need more frequent watering and organic matter to retain nutrients.

Barnwell County, SC (Zone 8b) Long season
233 days
Last Spring Frost March 22
233 growing days
First Fall Frost November 10

Barnwell County Soil Profile

Soil Type

Sandy Loam

Soil pH

5-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (96 days to spare)
Transplant: Mar 18 🍅 Harvest: May 20 – Jul 29
Recommended (50%) ✓ Fits season (93 days to spare)
Transplant: Mar 29 🍅 Harvest: May 31 – Aug 9
Safe Start (90%) ✓ Fits season (93 days to spare)
Transplant: Apr 15 🍅 Harvest: Jun 17 – Aug 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 Barnwell County

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

Soil pH

Your soil pH (5.0–6.3) is more acidic than Comfrey prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

Sandy soil in Barnwell County warms quickly in spring but drains fast. Comfrey will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Comfrey.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Comfrey.

How to Plant Comfrey

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

Succession Planting Comfrey

4
successive plantings in your 233-day season

Sow every 6.9 weeks. Last sowing by Aug 12 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 3.8" 0" ❄️ Dormant
Feb 4.1" 0" ❄️ Dormant
Mar 4.3" 4.5" 0" ✅ Rainfall sufficient
Apr 4.3" 3.9" 0.4" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 5.2" 0" ✅ Rainfall sufficient
Aug 4.3" 5" 0" ✅ Rainfall sufficient
Sep 4.3" 3.9" 0.4" 💧 Light watering
Oct 4.3" 2.8" 1.5" 💧 Light watering
Nov 4.3" 3.9" 0.4" 💧 Light watering
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Barnwell 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 ~1,706 GDD — county provides 5,300 GDD Excellent fit

Comfrey Planting Timeline — Barnwell County, SC

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors March 29 Mar 29 – Apr 12
Harvest May 31 May 31 – Aug 9

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 8b

📆 Growing Season

233 days in Barnwell County

Growing Tips for Comfrey in Barnwell County

Direct sow Comfrey outdoors after March 22 in Barnwell County when soil has warmed and frost danger has passed.

Sandy soil in Barnwell County dries quickly — mulch Comfrey with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 97°F in Barnwell County, provide afternoon shade for Comfrey and water deeply in the morning.

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 Barnwell County, SC?

Barnwell County is in Zone 8b with an average last frost of March 22. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Barnwell County, SC?

Barnwell County, South Carolina is in USDA Hardiness Zone 8b. The average last spring frost is March 22 and first fall frost is November 10.

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Your Barnwell County Garden Planner — Free

A 24-page printable planner built for Barnwell County (Zone 8b). 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 Barnwell County, SC. Local conditions may vary. Last updated: May 2026.

Sources & credits

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