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When to plant Comfrey in Sidell,

In Sidell, Comfrey is a spring-only crop. Plant April 21–May 5 once soil hits 50°F.

When to Plant Comfrey in Sidell, IL

Sidell, IL Zone 6a June

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June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Sidell, IL.

Avg. last frost April 14
Avg. first frost October 16
Soil temp (4") 68°F
Watering Moderate
Pest pressure High
Daylight 14.8 hrs
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  • 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.

Sidell, Illinois is in USDA Zone 6a. The average last spring frost is April 14 and the first fall frost is October 16, giving you a growing season of approximately 185 days.

At an elevation of 1,218 feet, Vermilion County receives approximately 31.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Comfrey during the growing season.

Sidell, IL (Zone 6a) Moderate season
185 days
Last Spring Frost April 14
185 growing days
First Fall Frost October 16
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Sidell Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Comfrey Planting Risk Windows

Early Start (70% safe) ✓ Fits season (43 days to spare)
Transplant: Apr 18 🍅 Harvest: Jun 20 – Aug 29
Recommended (50%) ✓ Fits season (45 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 23 – Sep 1
Safe Start (90%) ✓ Fits season (40 days to spare)
Transplant: May 10 🍅 Harvest: Jul 12 – Sep 20

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 Sidell

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

Soil pH

Your soil pH (6.2–6.9) is within Comfrey's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.2%) — 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 185-day season

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

Comfrey Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 576 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.4" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 3.9" 0.4" 💧 Light watering
Jun 4.3" 3.7" 0.6" 💧 Light watering
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.5" 1.8" 💧 Light watering
Oct 4.3" 2.1" 2.2" 🚿 Regular watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Vermilion 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 ~1,031 GDD — county provides 2,543 GDD Excellent fit

Comfrey Planting Timeline — Sidell, IL

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors April 21 Apr 21 – May 5
Harvest June 23 Jun 23 – Sep 1

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 · 1-2 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

185 days in Vermilion County

Growing Tips for Comfrey in Sidell

Direct sow Comfrey outdoors after April 14 in Vermilion 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 →

When should I plant Comfrey in Sidell, ?

In Sidell, , plant Comfrey after the last frost (around April 14) and before the first frost (around October 16). Best results when soil holds above 50°F.

What growing zone is Sidell, for Comfrey?

Sidell sits in USDA Zone 6a. Comfrey grows reliably in zones 3a through 9b, so it's a good fit here.

Can Comfrey grow in Sidell's climate?

Yes — Comfrey grows well in Sidell's temperate climate. Sidell averages a 185-day frost-free season, with last frost around April 14 and first frost around October 16.

🌱

Your Vermilion County Garden Planner — Free

A 22-page printable planner built for Vermilion 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 Vermilion County, IL. Local conditions may vary. Last updated: June 2026.