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When to Plant Thai Basil in Cornish, UT

Cornish, UT Zone 6a June

Top priorities for Cornish, UT gardeners in June

A quick June briefing for Cornish, UT gardeners — what's urgent, what's next, and what can wait.

Avg. last frost June 11
Avg. first frost September 2
Soil temp (4") 52°F
Watering Critical
Pest pressure High
Daylight 15 hrs
  1. Set out thai basil seedlings

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Seed thai basil outdoors

    These tolerate cool soil, so you're not gambling by sowing now.

Looking ahead to July
  • Starting indoors: 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.

Cornish, Utah is in USDA Zone 6a. The average last spring frost is June 11 and the first fall frost is September 2, giving you a growing season of approximately 83 days.

At an elevation of 6,265 feet, Cache County receives approximately 15.5 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.

Cornish, UT (Zone 6a) Very short season
83 days
Last Spring Frost June 11
83 growing days
First Fall Frost September 2
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Cornish Soil Profile

Soil Type

Loam

Soil pH

6.6-8.4

Drainage

Well Drained

Thai Basil Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 27 Transplant: May 29 🍅 Harvest: Jul 24 – Sep 25
Recommended (50%) ✗ May not fit
Start indoors: Apr 23 Transplant: Jun 25 🍅 Harvest: Aug 20 – Oct 22
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jul 8 🍅 Harvest: Sep 2 – Nov 4

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 Cornish

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

Soil pH

Your soil pH (6.6–8.4) is more alkaline than Thai Basil prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Cache County is excellent for Thai Basil — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Thai Basil.

How to Plant Thai Basil

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

Thai Basil Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 191 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 1.1" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.7" 0" ❄️ Dormant
May 2" 0" ❄️ Dormant
Jun 4.3" 1.1" 3.2" 🚿 Regular watering
Jul 4.3" 1.3" 3" 🚿 Regular watering
Aug 4.3" 1.5" 2.8" 🚿 Regular watering
Sep 4.3" 1.3" 3" 🚿 Regular watering
Oct 1.4" 0" ❄️ Dormant
Nov 1.1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Cache 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 ~812 GDD — county provides 1,079 GDD Excellent fit

Thai Basil Planting Timeline — Cornish, UT

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors April 23 Apr 23 – May 7
Transplant Outdoors June 25 Jun 25 – Jul 9
Direct Sow June 18 Jun 18 – Jul 9
Harvest August 20 Aug 20 – Oct 22

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6a

📆 Growing Season

83 days in Cache County

Growing Tips for Thai Basil in Cornish

Direct sow Thai Basil outdoors after June 11 in Cache County when soil has warmed and frost danger has passed.

Cache County receives only 16" of rain annually. Thai Basil needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 →

🌱

Your Cache County Garden Planner — Free

A 22-page printable planner built for Cache 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 Cache County, UT. Local conditions may vary. Last updated: June 2026.