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When to plant Comfrey in Saint Libory, IL

Saint Libory sits in cold Zone 7a. Plant Comfrey April 9–April 23 for the single annual harvest; the November 2 first frost closes the window.

When to Plant Comfrey in Saint Libory, IL

St. Clair County, Illinois Zone 7a June

St. Clair County, Illinois gardeners: here's your June plan

A quick June briefing for St. Clair County, Illinois gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 2
Avg. first frost November 2
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 14.7 hrs
  1. It's harvest week for comfrey

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

July prep starts now
  • 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.

Saint Libory, Illinois is in USDA Zone 7a. The average last spring frost is April 2 and the first fall frost is November 2, giving you a growing season of approximately 214 days.

At an elevation of 711 feet, St. Clair County receives approximately 34.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Comfrey during the growing season.

Saint Libory, IL (Zone 7a) Long season
214 days
Last Spring Frost April 2
214 growing days
First Fall Frost November 2

Saint Libory Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.3

Drainage

Well Drained

Comfrey Planting Risk Windows

Early Start (70% safe) ✓ Fits season (76 days to spare)
Transplant: Apr 2 🍅 Harvest: Jun 4 – Aug 13
Recommended (50%) ✓ Fits season (74 days to spare)
Transplant: Apr 9 🍅 Harvest: Jun 11 – Aug 20
Safe Start (90%) ✓ Fits season (80 days to spare)
Transplant: Apr 24 🍅 Harvest: Jun 26 – Sep 4

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 Saint Libory

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

Soil pH

Your soil pH (6.0–7.3) overlaps with Comfrey's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — Comfrey will thrive.

How to Plant Comfrey

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

Succession Planting Comfrey

4
successive plantings in your 214-day season

Sow every 6.9 weeks. Last sowing by Aug 04 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 756 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 1.5" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 4" 0.3" 💧 Light watering
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3.9" 0.4" 💧 Light watering
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 2.5" 1.8" 💧 Light watering
Nov 4.3" 2.4" 1.9" 💧 Light watering
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in St. Clair 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 ~1,256 GDD — county provides 3,584 GDD Excellent fit

Comfrey Planting Timeline — Saint Libory, IL

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors April 9 Apr 9 – Apr 23
Harvest June 11 Jun 11 – Aug 20

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

Month-by-Month Timeline

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

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: acceptable

🗺️ USDA Zone

Zone 7a

📆 Growing Season

214 days in St. Clair County

Growing Tips for Comfrey in Saint Libory

Direct sow Comfrey outdoors after April 02 in St. Clair 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 Saint Libory, IL?

In Saint Libory, IL, plant Comfrey after the last frost (around April 2) and before the first frost (around November 2). Best results when soil holds above 50°F.

What growing zone is Saint Libory, IL for Comfrey?

Saint Libory sits in USDA Zone 7a. Comfrey grows reliably in zones 3a through 9b, so it's a good fit here.

Can Comfrey grow in Saint Libory's climate?

Yes — Comfrey grows well in Saint Libory's temperate climate. Saint Libory averages a 214-day frost-free season, with last frost around April 2 and first frost around November 2.

🌱

Your St. Clair County Garden Planner — Free

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