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When to Plant Comfrey in Chouteau County, MT

Chouteau County, Montana Zone 4a May

May to-do list for Chouteau County, Montana

Each item below is timed to Chouteau County, Montana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 12
Avg. first frost September 27
Soil temp (4") 37°F
Watering High
Pest pressure Low
Daylight 14.9 hrs
  1. Harden off and plant comfrey

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

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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.

Chouteau County, Montana is in USDA Zone 4a. The average last spring frost is May 12 and the first fall frost is September 27, giving you a growing season of approximately 138 days.

At an elevation of 5,753 feet, Chouteau County receives approximately 15 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Comfrey to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Comfrey successfully. Mulch heavily to conserve soil moisture.

Chouteau County, MT (Zone 4a) Short season
138 days
Last Spring Frost May 12
138 growing days
First Fall Frost September 27

Chouteau County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.8

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 19 🍅 Harvest: Jul 21 – Sep 29
Safe Start (90%) ✗ May not fit
Transplant: Jun 9 🍅 Harvest: Aug 11 – Oct 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 Chouteau County

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

Soil pH

Your soil pH (6.4–7.8) is more alkaline than Comfrey prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). 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 138-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
0.5″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 801 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" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 4.3" 1.7" 2.6" 🚿 Regular watering
Jun 4.3" 1.2" 3.1" 🚿 Regular watering
Jul 4.3" 1.4" 2.9" 🚿 Regular watering
Aug 4.3" 1.8" 2.5" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 0.9" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Chouteau 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 ~975 GDD — county provides 1,794 GDD Excellent fit

Comfrey Planting Timeline — Chouteau County, MT

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 19 May 19 – Jun 2
Harvest July 21 Jul 21 – Sep 29

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 · 1-2 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4a

📆 Growing Season

138 days in Chouteau County

Growing Tips for Comfrey in Chouteau County

Direct sow Comfrey outdoors after May 12 in Chouteau County when soil has warmed and frost danger has passed.

Chouteau County receives only 15" of rain annually. Comfrey needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Chouteau County, MT?

Chouteau County is in Zone 4a with an average last frost of May 12. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Chouteau County, MT?

Chouteau County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 12 and first fall frost is September 27.

🌱

Your Chouteau County Garden Planner — Free

A 24-page printable planner built for Chouteau 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 Chouteau County, MT. Local conditions may vary. Last updated: May 2026.

Sources & credits

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