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When to Plant Comfrey in Treasure County, MT

Comfrey is a vigorous perennial herb valued as a dynamic accumulator of nutrients. Its leaves make excellent mulch, compost activator, and liquid fertilizer.

Treasure County, Montana is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is October 1, giving you a growing season of approximately 143 days.

At an elevation of 6,726 feet, Treasure County receives approximately 17.1 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, 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.

Treasure County, MT (Zone 4a) Short season
143 days
Last Spring Frost May 11
143 growing days
First Fall Frost October 1

Treasure County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (0 days to spare)
Transplant: May 12 🍅 Harvest: Jul 14 – Sep 22
Recommended (50%) ✓ Fits season (3 days to spare)
Transplant: May 18 🍅 Harvest: Jul 20 – Sep 28
Safe Start (90%) ✓ Fits season (4 days to spare)
Transplant: May 29 🍅 Harvest: Jul 31 – Oct 9

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 760 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Comfrey needs ~975 GDD — county provides 1,859 GDD Excellent fit

Comfrey Planting Timeline โ€” Treasure County, MT

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 18 May 18 โ€“ Jun 1
Harvest July 20 Jul 20 โ€“ Sep 28

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

143 days

Growing Tips for Treasure County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Comfrey in Treasure County, MT?

Treasure County is in Zone 4a with an average last frost of May 11. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Treasure County, MT?

Treasure County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Treasure County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

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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 Treasure County, MT. Local conditions may vary. Last updated: April 2026.