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When to Plant Comfrey in Douglas 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.

Douglas County, South Dakota is in USDA Zone 4b. The average last spring frost is May 1 and the first fall frost is October 6, giving you a growing season of approximately 158 days.

At an elevation of 737 feet, Douglas County receives approximately 34.5 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.

Douglas County, SD (Zone 4b) Moderate season
158 days
Last Spring Frost May 1
158 growing days
First Fall Frost October 6

Douglas County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (21 days to spare)
Transplant: May 1 🍅 Harvest: Jul 3 – Sep 11
Recommended (50%) ✓ Fits season (18 days to spare)
Transplant: May 8 🍅 Harvest: Jul 10 – Sep 18
Safe Start (90%) ✓ Fits season (15 days to spare)
Transplant: May 21 🍅 Harvest: Jul 23 – Oct 1

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
0.1″/week
Watering frequency Only during dry spells
Season total 140 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 1,817 GDD Excellent fit

Comfrey Planting Timeline โ€” Douglas County, SD

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 8 May 8 โ€“ May 22
Harvest July 10 Jul 10 โ€“ Sep 18

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 4b

Growing Season

158 days

Growing Tips for Douglas 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 Douglas County, SD?

Douglas County is in Zone 4b with an average last frost of May 1. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Douglas County, SD?

Douglas County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 1 and first fall frost is October 6.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Douglas 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 Douglas County, SD. Local conditions may vary. Last updated: April 2026.