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When to Plant Thai Basil in Carson County, TX

Carson County, Texas Zone 7a May

May in the garden — Carson County, Texas

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 14
Avg. first frost October 25
Soil temp (4") 64°F
Watering Critical
Pest pressure Moderate
Daylight 13.9 hrs
Coming up in June — start thinking about
  • Starting indoors: thai basil
  • First harvests: thai basil

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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.

Carson County, Texas is in USDA Zone 7a. The average last spring frost is April 14 and the first fall frost is October 25, giving you a growing season of approximately 194 days.

At an elevation of 2,585 feet, Carson County receives approximately 45.2 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 99°F, so Thai Basil may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Thai Basil will need more frequent watering and organic matter to retain nutrients.

Carson County, TX (Zone 7a) Moderate season
194 days
Last Spring Frost April 14
194 growing days
First Fall Frost October 25
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Carson County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.9-8.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (60 days to spare)
Start indoors: Feb 18 Transplant: Apr 22 🍅 Harvest: Jun 17 – Aug 19
Recommended (50%) ✓ Fits season (61 days to spare)
Start indoors: Feb 24 Transplant: Apr 28 🍅 Harvest: Jun 23 – Aug 25
Safe Start (90%) ✓ Fits season (57 days to spare)
Start indoors: Mar 13 Transplant: May 15 🍅 Harvest: Jul 10 – Sep 11

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 Carson County

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

Soil pH

Your soil pH (7.9–8.8) is more alkaline than Thai Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Carson County warms quickly in spring but drains fast. Thai Basil will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Thai Basil.

Organic Matter

Organic matter is low (1.0%). Add 2-3 inches of compost before planting Thai Basil.

How to Plant Thai Basil

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

Succession Planting Thai Basil

4
successive plantings in your 194-day season

Sow every 5.7 weeks. Last sowing by Aug 11 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 666 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 3.5" 0" ❄️ Dormant
Feb 2.5" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 4.3" 1.3" 3" 🚿 Regular watering
May 4.3" 1.1" 3.2" 🚿 Regular watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 7.6" 0" ✅ Rainfall sufficient
Aug 4.3" 9" 0" ✅ Rainfall sufficient
Sep 4.3" 6.6" 0" ✅ Rainfall sufficient
Oct 4.3" 4.1" 0.2" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Carson County). Supplement amounts are based on average rainfall — 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" — every day above 50°F 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 ~1,516 GDD — county provides 4,704 GDD Excellent fit

Thai Basil Planting Timeline — Carson County, TX

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 – Mar 10
Transplant Outdoors April 28 Apr 28 – May 12
Direct Sow April 21 Apr 21 – May 12
Harvest June 23 Jun 23 – Aug 25

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 7a

📆 Growing Season

194 days in Carson County

Growing Tips for Thai Basil in Carson County

Direct sow Thai Basil outdoors after April 14 in Carson County when soil has warmed and frost danger has passed.

Sandy soil in Carson County dries quickly — mulch Thai Basil with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 99°F in Carson County, provide afternoon shade for Thai Basil and water deeply in the morning.

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 Carson County, TX?

Carson County is in Zone 7a with an average last frost of April 14. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Carson County, TX?

Carson County, Texas is in USDA Hardiness Zone 7a. The average last spring frost is April 14 and first fall frost is October 25.

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Your Carson County Garden Planner — Free

A 24-page printable planner built for Carson County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Carson County, TX. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.