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When to Plant Horehound in Sullivan County, IN

Horehound is a woolly, drought-tolerant perennial herb traditionally used for cough remedies and candy. It has a distinctive bitter, menthol-like flavor.

Sullivan County, Indiana is in USDA Zone 6a. The average last spring frost is April 18 and the first fall frost is October 17, giving you a growing season of approximately 182 days.

At an elevation of 914 feet, Sullivan County receives approximately 34.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Horehound during the growing season.

Sullivan County, IN (Zone 6a) Moderate season
182 days
Last Spring Frost April 18
182 growing days
First Fall Frost October 17

Sullivan County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (41 days to spare)
Transplant: Apr 20 🍅 Harvest: Jul 6 – Aug 31
Recommended (50%) ✓ Fits season (42 days to spare)
Transplant: Apr 25 🍅 Harvest: Jul 11 – Sep 5
Safe Start (90%) ✓ Fits season (39 days to spare)
Transplant: May 11 🍅 Harvest: Jul 27 – Sep 21

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
0.5″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Horehound needs ~1,444 GDD — county provides 3,185 GDD Excellent fit

Horehound Planting Timeline โ€” Sullivan County, IN

Horehound Planting Calendar

Activity When Date Range
Transplant Outdoors April 25 Apr 25 โ€“ May 9
Harvest July 11 Jul 11 โ€“ Sep 5

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May Transplant Outdoors
June โ€”
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

75โ€“90 days

Soil pH

6 โ€“ 8

USDA Zone

Zone 6a

Growing Season

182 days

Growing Tips for Sullivan County

Direct sow or start from divisions. Thrives in poor, dry soil. Harvest stems just before flowering. Deadhead to prevent aggressive self-seeding. Very drought-tolerant once established.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Horehound in Sullivan County, IN?

Sullivan County is in Zone 6a with an average last frost of April 18. Plan your Horehound planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Sullivan County, IN?

Sullivan County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 18 and first fall frost is October 17.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Sullivan County gardeners in Zone 6a 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 Sullivan County, IN. Local conditions may vary. Last updated: April 2026.