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When to Plant Thai Basil in Carbon County, UT

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.

Carbon County, Utah is in USDA Zone 6a. The average last spring frost is May 17 and the first fall frost is September 27, giving you a growing season of approximately 133 days.

At an elevation of 5,755 feet, Carbon County receives approximately 14.2 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Thai Basil to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Thai Basil successfully. Mulch heavily to conserve soil moisture.

Carbon County, UT (Zone 6a) Short season
133 days
Last Spring Frost May 17
133 growing days
First Fall Frost September 27

Carbon County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.3

Drainage

Well Drained

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 1" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.2" 0" ❄️ Dormant
Apr 1.5" 0" ❄️ Dormant
May 4.3" 1.8" 2.5" 🚿 Regular watering
Jun 4.3" 1.1" 3.2" 🚿 Regular watering
Jul 4.3" 1.3" 3" 🚿 Regular watering
Aug 4.3" 1.3" 3" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 0.9" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Carbon County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Thai Basil Planting Timeline — Carbon County, UT

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 31 May 31 – Jun 14
Direct Sow May 24 May 24 – Jun 14
Harvest July 26 Jul 26 – Sep 27

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: N/A

🗺️ USDA Zone

Zone 6a

📆 Growing Season

133 days in Carbon County

Growing Tips for Carbon 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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Thai Basil in Carbon County, UT?

Carbon County is in Zone 6a with an average last frost of May 17. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Carbon County, UT?

Carbon County, Utah is in USDA Hardiness Zone 6a. The average last spring frost is May 17 and first fall frost is September 27.

🌱

Your Carbon County Garden Planner — Free

A 22-page printable planner built for Carbon County (Zone 6a). 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 Carbon County, UT. Local conditions may vary. Last updated: August 2026.

Sources & credits

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