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When to Plant Comfrey in Renville County, ND

Renville County, North Dakota Zone 4a April

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Avg. last frost May 13
Avg. first frost September 27
Soil temp (4") 37°F
Watering None
Pest pressure Low
Daylight 13.5 hrs
Get ahead of May
  • Transplants going out: 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.

Renville County, North Dakota is in USDA Zone 4a. The average last spring frost is May 13 and the first fall frost is September 27, giving you a growing season of approximately 137 days.

At an elevation of 747 feet, Renville County receives approximately 29.5 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Comfrey to ensure they mature before fall.

Renville County, ND (Zone 4a) Short season
137 days
Last Spring Frost May 13
137 growing days
First Fall Frost September 27

Renville County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 15 🍅 Harvest: Jul 17 – Sep 25
Recommended (50%) ✗ May not fit
Transplant: May 20 🍅 Harvest: Jul 22 – Sep 30
Safe Start (90%) ✗ May not fit
Transplant: Jun 2 🍅 Harvest: Aug 4 – Oct 13

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 Renville County

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

Soil pH

Your soil pH (6.4–7.2) overlaps with Comfrey's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.8%). Annual compost additions will help Comfrey.

How to Plant Comfrey

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

Succession Planting Comfrey

2
successive plantings in your 137-day season

Sow every 6.9 weeks. Last sowing by Jun 29 to harvest before frost.

Plant 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 140 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 1.9" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 4.3" 3.2" 1.1" 💧 Light watering
Jun 4.3" 2.2" 2.1" 💧 Light watering
Jul 4.3" 2.8" 1.5" 💧 Light watering
Aug 4.3" 2.8" 1.5" 💧 Light watering
Sep 4.3" 2.2" 2.1" 💧 Light watering
Oct 2.5" 0" ❄️ Dormant
Nov 2.2" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Renville 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 ~806 GDD — county provides 1,472 GDD Excellent fit

Comfrey Planting Timeline — Renville County, ND

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 20 May 20 – Jun 3
Harvest July 22 Jul 22 – Sep 30

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June Transplant Outdoors
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: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

137 days in Renville County

Growing Tips for Comfrey in Renville County

Direct sow Comfrey outdoors after May 13 in Renville 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 Renville County, ND?

Renville County is in Zone 4a with an average last frost of May 13. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Renville County, ND?

Renville County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 13 and first fall frost is September 27.

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Your Renville County Garden Planner — Free

A 24-page printable planner built for Renville County (Zone 4a). 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 Renville County, ND. Local conditions may vary. Last updated: April 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.