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When to Plant Comfrey in Niobrara County, WY

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

Niobrara County, Wyoming is in USDA Zone 4b. The average last spring frost is May 15 and the first fall frost is September 21, giving you a growing season of approximately 129 days.

At an elevation of 5,262 feet, Niobrara County receives approximately 19.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82ยฐF, 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.

Niobrara County, WY (Zone 4b) Short season
129 days
Last Spring Frost May 15
129 growing days
First Fall Frost September 21

Niobrara County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 20 🍅 Harvest: Jul 22 – Sep 30
Recommended (50%) ✗ May not fit
Transplant: May 22 🍅 Harvest: Jul 24 – Oct 2
Safe Start (90%) ✗ May not fit
Transplant: Jun 11 🍅 Harvest: Aug 13 – Oct 22

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
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 503 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Comfrey needs ~862 GDD — county provides 1,483 GDD Excellent fit

Comfrey Planting Timeline โ€” Niobrara County, WY

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 22 May 22 โ€“ Jun 5
Harvest July 24 Jul 24 โ€“ Oct 2

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 Harvest
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 4b

Growing Season

129 days

Growing Tips for Niobrara 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 Niobrara County, WY?

Niobrara County is in Zone 4b with an average last frost of May 15. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Niobrara County, WY?

Niobrara County, Wyoming is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 21.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Niobrara County gardeners in Zone 4b 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 Niobrara County, WY. Local conditions may vary. Last updated: April 2026.