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When to Plant Thai Basil in Clark County, KS

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.

Clark County, Kansas is in USDA Zone 6b. The average last spring frost is April 16 and the first fall frost is October 22, giving you a growing season of approximately 189 days.

At an elevation of 867 feet, Clark County receives approximately 22.3 inches of rainfall annually with predominantly loam soil. Summer highs average 92ยฐF, providing good warmth for Thai Basil during the growing season.

Clark County, KS (Zone 6b) Moderate season
189 days
Last Spring Frost April 16
189 growing days
First Fall Frost October 22

Clark County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (54 days to spare)
Start indoors: Feb 21 Transplant: Apr 25 🍅 Harvest: Jun 20 – Aug 22
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Feb 26 Transplant: Apr 30 🍅 Harvest: Jun 25 – Aug 27
Safe Start (90%) ✓ Fits season (55 days to spare)
Start indoors: Mar 12 Transplant: May 14 🍅 Harvest: Jul 9 – Sep 10

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 Clark County

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

Soil pH

Your soil pH (6.8โ€“7.6) is more alkaline than Thai Basil prefers (6.0โ€“7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Clark 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

4
successive plantings in your 189-day season

Sow every 5.7 weeks. Last sowing by Aug 08 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,624 gal / 100 sq ft
Drought risk

Water stress score is 8/10 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€” 0.6" 0" โ„๏ธ Dormant
Feb โ€” 0.8" 0" โ„๏ธ Dormant
Mar โ€” 1.2" 0" โ„๏ธ Dormant
Apr 4.3" 2" 2.3" ๐Ÿšฟ Regular watering
May 4.3" 3.4" 0.9" ๐Ÿ’ง Light watering
Jun 4.3" 3.7" 0.6" ๐Ÿ’ง Light watering
Jul 4.3" 3.1" 1.2" ๐Ÿ’ง Light watering
Aug 4.3" 3" 1.3" ๐Ÿ’ง Light watering
Sep 4.3" 1.9" 2.4" ๐Ÿšฟ Regular watering
Oct 4.3" 1.2" 3.1" ๐Ÿšฟ Regular watering
Nov โ€” 0.8" 0" โ„๏ธ Dormant
Dec โ€” 0.5" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Aprโ€“Oct in Clark 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 ~1,188 GDD — county provides 3,591 GDD Excellent fit

Thai Basil Planting Timeline โ€” Clark County, KS

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors February 26 Feb 26 โ€“ Mar 12
Transplant Outdoors April 30 Apr 30 โ€“ May 14
Direct Sow April 23 Apr 23 โ€“ May 14
Harvest June 25 Jun 25 โ€“ Aug 27

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

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
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: too_alkaline

๐Ÿ—บ๏ธ USDA Zone

Zone 6b

๐Ÿ“† Growing Season

189 days in Clark County

Growing Tips for Thai Basil in Clark County

Direct sow Thai Basil outdoors after April 16 in Clark County when soil has warmed and frost danger has passed.

Clark County receives only 22" of rain annually. Thai Basil needs consistent moisture โ€” 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 →

Frequently Asked Questions

When should I plant Thai Basil in Clark County, KS?

Clark County is in Zone 6b with an average last frost of April 16. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Clark County, KS?

Clark County, Kansas is in USDA Hardiness Zone 6b. The average last spring frost is April 16 and first fall frost is October 22.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Clark County gardeners in Zone 6b 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 Clark County, KS. Local conditions may vary. Last updated: April 2026.