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When to Plant Thai Basil in Carter County, OK

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.

Carter County, Oklahoma is in USDA Zone 7b. The average last spring frost is March 28 and the first fall frost is November 2, giving you a growing season of approximately 219 days.

At an elevation of 648 feet, Carter County receives approximately 34.2 inches of rainfall annually with predominantly loam soil. Summer highs average 93ยฐF, providing good warmth for Thai Basil during the growing season.

Carter County, OK (Zone 7b) Long season
219 days
Last Spring Frost March 28
219 growing days
First Fall Frost November 2

Carter County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (88 days to spare)
Start indoors: Jan 31 Transplant: Apr 4 🍅 Harvest: May 30 – Aug 1
Recommended (50%) ✓ Fits season (86 days to spare)
Start indoors: Feb 7 Transplant: Apr 11 🍅 Harvest: Jun 6 – Aug 8
Safe Start (90%) ✓ Fits season (87 days to spare)
Start indoors: Feb 27 Transplant: May 1 🍅 Harvest: Jun 26 – Aug 28

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.

Soil Compatibility in Carter County

How your county's soil matches Thai Basil's growing requirements.

Soil pH

Your soil pH (6.4โ€“7.5) overlaps with Thai Basil's range (6.0โ€“7.0), though not a perfect match.

Soil Texture

The loam soil in Carter County is excellent for Thai Basil โ€” good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Thai Basil.

Organic Matter

Organic matter is moderate (3.3%). Annual compost additions will help Thai Basil.

How to Plant Thai Basil

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Thai Basil

5
successive plantings in your 219-day season

Sow every 5.7 weeks. Last sowing by Aug 19 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,507 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Monthly Watering Guide for Thai Basil

Thai Basil needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Thai Basil Needs Rainfall You Supplement Action
Jan โ€” 0.8" 0" โ„๏ธ Dormant
Feb โ€” 1.3" 0" โ„๏ธ Dormant
Mar 4.3" 1.9" 2.4" ๐Ÿšฟ Regular watering
Apr 4.3" 3.1" 1.2" ๐Ÿ’ง Light watering
May 4.3" 5.8" 0" โœ… Rainfall sufficient
Jun 4.3" 6" 0" โœ… Rainfall sufficient
Jul 4.3" 4.3" 0" โœ… Rainfall sufficient
Aug 4.3" 3.9" 0.4" ๐Ÿ’ง Light watering
Sep 4.3" 2.8" 1.5" ๐Ÿ’ง Light watering
Oct 4.3" 2.3" 2" ๐Ÿ’ง Light watering
Nov 4.3" 1.2" 3.1" ๐Ÿšฟ Regular watering
Dec โ€” 0.9" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Marโ€“Nov in Carter County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Thai Basil Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" โ€” every day above 50ยฐF deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Thai Basil needs ~1,234 GDD — county provides 4,325 GDD Excellent fit

Thai Basil Planting Timeline โ€” Carter County, OK

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors February 7 Feb 7 โ€“ Feb 21
Transplant Outdoors April 11 Apr 11 โ€“ Apr 25
Direct Sow April 4 Apr 4 โ€“ Apr 25
Harvest June 6 Jun 6 โ€“ Aug 8

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

Month-by-Month Timeline

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

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท 2-3 times/week

๐Ÿ“… Days to Maturity

50โ€“75 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 7b

๐Ÿ“† Growing Season

219 days in Carter County

Growing Tips for Thai Basil in Carter County

Direct sow Thai Basil outdoors after March 28 in Carter County when soil has warmed and frost danger has passed.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Thai Basil in Carter County, OK?

Carter County is in Zone 7b with an average last frost of March 28. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Carter County, OK?

Carter County, Oklahoma is in USDA Hardiness Zone 7b. The average last spring frost is March 28 and first fall frost is November 2.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Carter County gardeners in Zone 7b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

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 Carter County, OK. Local conditions may vary. Last updated: April 2026.