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When to plant Comfrey in Delavan, IL

Delavan's short 179-day growing season means one Comfrey planting between April 26 and May 10. No fall crop in Zone 6a.

When to Plant Comfrey in Delavan, IL

Tazewell County, Illinois Zone 6a June

June in Tazewell County, Illinois — your action list

Welcome to June in Zone 6a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 19
Avg. first frost October 15
Soil temp (4") 70°F
Watering Low
Pest pressure High
Daylight 14.9 hrs
  1. Harvest comfrey as they ripen

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

July 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.

Delavan, Illinois is in USDA Zone 6a. The average last spring frost is April 19 and the first fall frost is October 15, giving you a growing season of approximately 179 days.

At an elevation of 1,006 feet, Tazewell County receives approximately 40 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Comfrey during the growing season.

Delavan, IL (Zone 6a) Moderate season
179 days
Last Spring Frost April 19
179 growing days
First Fall Frost October 15

Delavan Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.9

Drainage

Well Drained

Comfrey Planting Risk Windows

Early Start (70% safe) ✓ Fits season (38 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 23 – Sep 1
Recommended (50%) ✓ Fits season (39 days to spare)
Transplant: Apr 26 🍅 Harvest: Jun 28 – Sep 6
Safe Start (90%) ✓ Fits season (38 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 Delavan

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

Soil pH

Your soil pH (6.3–6.9) is within Comfrey's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — 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 179-day season

Sow every 6.9 weeks. Last sowing by Jul 17 to harvest before frost.

Comfrey 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 98 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 1.9" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 4.3" 3.9" 0.4" 💧 Light watering
May 4.3" 5.2" 0" ✅ Rainfall sufficient
Jun 4.3" 5.1" 0" ✅ Rainfall sufficient
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 4.7" 0" ✅ Rainfall sufficient
Sep 4.3" 3.3" 1" 💧 Light watering
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Tazewell 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 2,729 GDD Excellent fit

Comfrey Planting Timeline — Delavan, IL

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors April 26 Apr 26 – May 10
Harvest June 28 Jun 28 – Sep 6

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

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

179 days in Tazewell County

Growing Tips for Comfrey in Delavan

Direct sow Comfrey outdoors after April 19 in Tazewell 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 Delavan, IL?

In Delavan, IL, plant Comfrey after the last frost (around April 19) and before the first frost (around October 15). Best results when soil holds above 50°F.

What growing zone is Delavan, IL for Comfrey?

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

Can Comfrey grow in Delavan's climate?

Yes — Comfrey grows well in Delavan's temperate climate. Delavan averages a 179-day frost-free season, with last frost around April 19 and first frost around October 15.

🌱

Your Tazewell County Garden Planner — Free

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