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When to Plant Comfrey in Clark 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.

Clark County, South Dakota is in USDA Zone 4a. The average last spring frost is May 3 and the first fall frost is October 5, giving you a growing season of approximately 155 days.

At an elevation of 799 feet, Clark County receives approximately 28.2 inches of rainfall annually with predominantly loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Comfrey to ensure they mature before fall.

Clark County, SD (Zone 4a) Moderate season
155 days
Last Spring Frost May 3
155 growing days
First Fall Frost October 5

Clark County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (14 days to spare)
Transplant: May 4 🍅 Harvest: Jul 6 – Sep 14
Recommended (50%) ✓ Fits season (15 days to spare)
Transplant: May 10 🍅 Harvest: Jul 12 – Sep 20
Safe Start (90%) ✓ Fits season (13 days to spare)
Transplant: May 22 🍅 Harvest: Jul 24 – Oct 2

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
0.5″/week
Watering frequency 1-2 times/week
Season total 739 gal / 100 sq ft
Comfrey needs ~806 GDD — county provides 1,666 GDD Excellent fit

Comfrey Planting Timeline โ€” Clark County, SD

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors May 10 May 10 โ€“ May 24
Harvest July 12 Jul 12 โ€“ Sep 20

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 4a

Growing Season

155 days

Growing Tips for Clark 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 Clark County, SD?

Clark County is in Zone 4a with an average last frost of May 3. Plan your Comfrey planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Clark County, SD?

Clark County, South Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 3 and first fall frost is October 5.

๐ŸŒฑ

Plan Your Garden with Confidence

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