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When to Plant Comfrey in Custer County, SD

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

Custer County, South Dakota is in USDA Zone 4b. The average last spring frost is May 14 and the first fall frost is October 2, giving you a growing season of approximately 141 days.

At an elevation of 868 feet, Custer County receives approximately 29.4 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.

Custer County, SD (Zone 4b) Short season
141 days
Last Spring Frost May 14
141 growing days
First Fall Frost October 2

Custer County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 17 🍅 Harvest: Jul 19 – Sep 27
Recommended (50%) ✓ Fits season (1 days to spare)
Transplant: May 21 🍅 Harvest: Jul 23 – Oct 1
Safe Start (90%) ✓ Fits season (1 days to spare)
Transplant: May 31 🍅 Harvest: Aug 2 – Oct 11

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
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 187 gal / 100 sq ft
Drought risk

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

Comfrey needs ~975 GDD — county provides 1,833 GDD Excellent fit

Comfrey Planting Timeline โ€” Custer County, SD

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 21 May 21 โ€“ Jun 4
Harvest July 23 Jul 23 โ€“ Oct 1

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

141 days

Growing Tips for Custer 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 Custer County, SD?

Custer County is in Zone 4b with an average last frost of May 14. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Custer County, SD?

Custer County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 14 and first fall frost is October 2.

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Plan Your Garden with Confidence

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