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When to plant Thai Basil in Jefferson County, KY

Jefferson County gardeners should plant Thai Basil between April 14 and May 5 in spring. With Jefferson County's Zone 7a climate (last frost April 7), Thai Basil needs 50–75 days to mature — plant by August 16 for a full harvest.

When to Plant Thai Basil in Jefferson County, KY

Jefferson County, Kentucky Zone 7a June

Your June gardening checklist

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Avg. last frost April 7
Avg. first frost October 30
Soil temp (4") 66°F
Watering Low
Pest pressure High
Daylight 14.6 hrs

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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.

Jefferson County, Kentucky is in USDA Zone 7a. The average last spring frost is April 7 and the first fall frost is October 30, giving you a growing season of approximately 206 days.

At an elevation of 3,279 feet, Jefferson County receives approximately 43.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Thai Basil during the growing season.

Jefferson County, KY (Zone 7a) Long season
206 days
Last Spring Frost April 7
206 growing days
First Fall Frost October 30

Jefferson County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.6

Drainage

Well Drained

Thai Basil Planting Risk Windows

Early Start (70% safe) ✓ Fits season (75 days to spare)
Start indoors: Feb 8 Transplant: Apr 12 🍅 Harvest: Jun 7 – Aug 9
Recommended (50%) ✓ Fits season (73 days to spare)
Start indoors: Feb 17 Transplant: Apr 21 🍅 Harvest: Jun 16 – Aug 18
Safe Start (90%) ✓ Fits season (67 days to spare)
Start indoors: Mar 6 Transplant: May 8 🍅 Harvest: Jul 3 – Sep 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 Jefferson County

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

Soil pH

Your soil pH (5.2–6.6) is more acidic than Thai Basil prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). 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

4
successive plantings in your 206-day season

Sow every 5.7 weeks. Last sowing by Aug 16 to harvest before frost.

Thai Basil Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 222 gal / 100 sq ft

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 3.2" 0" ❄️ Dormant
Feb 3.2" 0" ❄️ Dormant
Mar 4.5" 0" ❄️ Dormant
Apr 4.3" 2.9" 1.4" 💧 Light watering
May 4.3" 3.6" 0.7" 💧 Light watering
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 3.9" 0.4" 💧 Light watering
Aug 4.3" 4.5" 0" ✅ Rainfall sufficient
Sep 4.3" 3.7" 0.6" 💧 Light watering
Oct 4.3" 2.5" 1.8" 💧 Light watering
Nov 3.2" 0" ❄️ Dormant
Dec 3.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Jefferson 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 ~859 GDD — county provides 2,832 GDD Excellent fit

Thai Basil Planting Timeline — Jefferson County, KY

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors February 17 Feb 17 – Mar 3
Transplant Outdoors April 21 Apr 21 – May 5
Direct Sow April 14 Apr 14 – May 5
Harvest June 16 Jun 16 – Aug 18

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

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_acidic

🗺️ USDA Zone

Zone 7a

📆 Growing Season

206 days in Jefferson County

Growing Tips for Thai Basil in Jefferson County

Direct sow Thai Basil outdoors after April 07 in Jefferson 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 Jefferson County, KY?

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

What planting zone is Jefferson County, KY?

Jefferson County, Kentucky is in USDA Hardiness Zone 7a. The average last spring frost is April 7 and first fall frost is October 30.

When should I plant Thai Basil in Jefferson County, KY?

In Jefferson County, KY, plant Thai Basil after the last frost (around April 7) and before the first frost (around October 30). Best results when soil holds above 50°F.

What growing zone is Jefferson County, KY for Thai Basil?

Jefferson County sits in USDA Zone 7a. Thai Basil grows reliably in zones 4a through 11b, so it's a good fit here.

Can Thai Basil grow in Jefferson County's climate?

Yes — Thai Basil grows well in Jefferson County's temperate climate. Jefferson County averages a 206-day frost-free season, with last frost around April 7 and first frost around October 30.

🌱

Your Jefferson County Garden Planner — Free

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

Sources & credits

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