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When to Plant Comfrey in San Juan 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.

San Juan County, Utah is in USDA Zone 5b. The average last spring frost is May 2 and the first fall frost is October 11, giving you a growing season of approximately 162 days.

At an elevation of 5,225 feet, San Juan County receives approximately 13.7 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.

San Juan County, UT (Zone 5b) Moderate season
162 days
Last Spring Frost May 2
162 growing days
First Fall Frost October 11

San Juan County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (27 days to spare)
Transplant: Apr 27 🍅 Harvest: Jun 29 – Sep 7
Recommended (50%) ✓ Fits season (22 days to spare)
Transplant: May 9 🍅 Harvest: Jul 11 – Sep 19
Safe Start (90%) ✓ Fits season (15 days to spare)
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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.4″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,116 gal / 100 sq ft
Drought risk

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

Comfrey needs ~975 GDD — county provides 2,106 GDD Excellent fit

Comfrey Planting Timeline โ€” San Juan County, UT

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 9 May 9 โ€“ May 23
Harvest July 11 Jul 11 โ€“ Sep 19

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 โ€”
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 5b

Growing Season

162 days

Growing Tips for San Juan 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 San Juan County, UT?

San Juan County is in Zone 5b with an average last frost of May 2. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is San Juan County, UT?

San Juan County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 2 and first fall frost is October 11.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help San Juan County gardeners in Zone 5b 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 San Juan County, UT. Local conditions may vary. Last updated: April 2026.