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When to Plant Comfrey in Box Elder County, UT

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

Box Elder County, Utah is in USDA Zone 6a. The average last spring frost is May 22 and the first fall frost is October 3, giving you a growing season of approximately 134 days.

At an elevation of 4,039 feet, Box Elder County receives approximately 24.5 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Comfrey during the growing season.

Box Elder County, UT (Zone 6a) Short season
134 days
Last Spring Frost May 22
134 growing days
First Fall Frost October 3

Box Elder County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 19 🍅 Harvest: Jul 21 – Sep 29
Recommended (50%) ✗ May not fit
Transplant: May 29 🍅 Harvest: Jul 31 – Oct 9
Safe Start (90%) ✗ May not fit
Transplant: Jun 17 🍅 Harvest: Aug 19 – Oct 28

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
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 332 gal / 100 sq ft
Drought risk

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

Comfrey needs ~1,144 GDD — county provides 2,043 GDD Excellent fit

Comfrey Planting Timeline โ€” Box Elder County, UT

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 29 May 29 โ€“ Jun 12
Harvest July 31 Jul 31 โ€“ Oct 9

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 6a

Growing Season

134 days

Growing Tips for Box Elder 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 Box Elder County, UT?

Box Elder County is in Zone 6a with an average last frost of May 22. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Box Elder County, UT?

Box Elder County, Utah is in USDA Hardiness Zone 6a. The average last spring frost is May 22 and first fall frost is October 3.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Box Elder County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Box Elder County, UT. Local conditions may vary. Last updated: April 2026.