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When to Plant Thai Basil in Terrebonne Parish, LA

Terrebonne Parish, Louisiana Zone 9b May

Your May gardening checklist

May is a pivotal month for Terrebonne Parish, Louisiana gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost February 7
Avg. first frost December 8
Soil temp (4") 78°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Pick thai basil

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

Before June arrives, get these ready
  • 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.

Terrebonne Parish, Louisiana is in USDA Zone 9b. The average last spring frost is February 7 and the first fall frost is December 8, giving you a growing season of approximately 304 days.

At an elevation of 484 feet, Terrebonne Parish receives approximately 61.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 102°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. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Thai Basil root diseases.

Terrebonne Parish, LA (Zone 9b) Year-round
304 days
Last Spring Frost February 7
304 growing days
First Fall Frost December 8
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Terrebonne Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

5.1-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (185 days to spare)
Start indoors: Dec 14 Transplant: Feb 1 🍅 Harvest: Mar 29 – May 31
Recommended (50%) ✓ Fits season (178 days to spare)
Start indoors: Dec 27 Transplant: Feb 14 🍅 Harvest: Apr 11 – Jun 13
Safe Start (90%) ✓ Fits season (163 days to spare)
Start indoors: Jan 25 Transplant: Mar 15 🍅 Harvest: May 10 – Jul 12

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 Terrebonne Parish

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

Soil pH

Your soil pH (5.1–6.4) is more acidic than Thai Basil prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

Sandy soil in Terrebonne Parish 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 (2.0%). 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

7
successive plantings in your 304-day season

Sow every 5.7 weeks. Last sowing by Sep 24 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 5.3" 0" ❄️ Dormant
Feb 4.3" 5.5" 0" ✅ Rainfall sufficient
Mar 4.3" 6.1" 0" ✅ Rainfall sufficient
Apr 4.3" 5" 0" ✅ Rainfall sufficient
May 4.3" 5" 0" ✅ Rainfall sufficient
Jun 4.3" 5.3" 0" ✅ Rainfall sufficient
Jul 4.3" 6.2" 0" ✅ Rainfall sufficient
Aug 4.3" 5.7" 0" ✅ Rainfall sufficient
Sep 4.3" 4.1" 0.2" 💧 Light watering
Oct 4.3" 3.7" 0.6" 💧 Light watering
Nov 4.3" 4.9" 0" ✅ Rainfall sufficient
Dec 4.3" 5.1" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Feb–Dec in Terrebonne Parish). 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 ~1,656 GDD — county provides 8,082 GDD Excellent fit

Thai Basil Planting Timeline — Terrebonne Parish, LA

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors December 27 Dec 27 – Jan 10
Transplant Outdoors February 14 Feb 14 – Feb 28
Direct Sow February 14 Feb 14 – Mar 7
Harvest April 11 Apr 11 – Jun 13

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9b

📆 Growing Season

304 days in Terrebonne Parish

Growing Tips for Thai Basil in Terrebonne Parish

Direct sow Thai Basil outdoors after February 07 in Terrebonne Parish when soil has warmed and frost danger has passed.

Sandy soil in Terrebonne Parish 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 102°F in Terrebonne Parish, 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 Terrebonne Parish, LA?

Terrebonne Parish is in Zone 9b with an average last frost of February 7. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Terrebonne Parish, LA?

Terrebonne Parish, Louisiana is in USDA Hardiness Zone 9b. The average last spring frost is February 7 and first fall frost is December 8.

🌱

Your Terrebonne Parish Garden Planner — Free

A 24-page printable planner built for Terrebonne Parish (Zone 9b). 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 Terrebonne Parish, LA. 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.