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When to Plant Thai Basil in Decatur County, IN

Thai basil has a distinctive anise-licorice flavor with sturdy purple stems and small leaves. It is essential in Thai, Vietnamese, and other Southeast Asian cuisines.

Decatur County, Indiana is in USDA Zone 6a. The average last spring frost is April 10 and the first fall frost is October 20, giving you a growing season of approximately 193 days.

At an elevation of 985 feet, Decatur County receives approximately 32.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Thai Basil during the growing season.

Decatur County, IN (Zone 6a) Moderate season
193 days
Last Spring Frost April 10
193 growing days
First Fall Frost October 20

Decatur County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (60 days to spare)
Start indoors: Feb 17 Transplant: Apr 21 🍅 Harvest: Jun 16 – Aug 18
Recommended (50%) ✓ Fits season (60 days to spare)
Start indoors: Feb 20 Transplant: Apr 24 🍅 Harvest: Jun 19 – Aug 21
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Mar 11 Transplant: May 13 🍅 Harvest: Jul 8 – Sep 9

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
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,018 gal / 100 sq ft
Thai Basil needs ~1,094 GDD — county provides 3,377 GDD Excellent fit

Thai Basil Planting Timeline โ€” Decatur County, IN

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors February 20 Feb 20 โ€“ Mar 6
Transplant Outdoors April 24 Apr 24 โ€“ May 8
Direct Sow April 17 Apr 17 โ€“ May 8
Harvest June 19 Jun 19 โ€“ Aug 21

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

50โ€“75 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6a

Growing Season

193 days

Growing Tips for Decatur County

Start seeds indoors or direct sow after last frost. Thai basil holds up better to heat in cooking than sweet basil. Pinch flowers to prolong leaf production.

Companion Planting

Good Companions

Avoid Planting Near

  • Rue
  • Sage

Level Up Your Garden

Frequently Asked Questions

When should I plant Thai Basil in Decatur County, IN?

Decatur County is in Zone 6a with an average last frost of April 10. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Decatur County, IN?

Decatur County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 10 and first fall frost is October 20.

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Plan Your Garden with Confidence

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