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When to Plant Thai Basil in Klamath County, OR

Klamath County, Oregon Zone 6b May

May in Klamath County, Oregon — your action list

Welcome to May in Zone 6b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost June 13
Avg. first frost September 21
Soil temp (4") 63°F
Watering Moderate
Pest pressure Low
Daylight 14.4 hrs
Get ahead of June
  • Transplants going out: thai basil
  • Direct-sowing: 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.

Klamath County, Oregon is in USDA Zone 6b. The average last spring frost is June 13 and the first fall frost is September 21, giving you a growing season of approximately 100 days.

At an elevation of 142 feet, Klamath County receives approximately 48.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Thai Basil to ensure they mature before fall.

Klamath County, OR (Zone 6b) Short season
100 days
Last Spring Frost June 13
100 growing days
First Fall Frost September 21

Klamath County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 11 Transplant: Jun 13 🍅 Harvest: Aug 8 – Oct 10
Recommended (50%) ✗ May not fit
Start indoors: Apr 25 Transplant: Jun 27 🍅 Harvest: Aug 22 – Oct 24
Safe Start (90%) ✗ May not fit
Start indoors: May 8 Transplant: Jul 10 🍅 Harvest: Sep 4 – Nov 6

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 Klamath County

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

Soil pH

Your soil pH (5.5–6.3) is more acidic than Thai Basil prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Thai Basil.

Organic Matter

Organic matter is excellent (5.1%) — Thai Basil will thrive.

How to Plant Thai Basil

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

Succession Planting Thai Basil

2
successive plantings in your 100-day season

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
2.1″/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 7.4" 0" ❄️ Dormant
Feb 5.2" 0" ❄️ Dormant
Mar 4.8" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 4.3" 1.8" 2.5" 🚿 Regular watering
Jul 4.3" 0.9" 3.4" 🚿 Regular watering
Aug 4.3" 0.8" 3.5" 🚿 Regular watering
Sep 4.3" 2.1" 2.2" 🚿 Regular watering
Oct 4.8" 0" ❄️ Dormant
Nov 7.7" 0" ❄️ Dormant
Dec 6.9" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Klamath 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 ~766 GDD — county provides 1,225 GDD Excellent fit

Thai Basil Planting Timeline — Klamath County, OR

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors April 25 Apr 25 – May 9
Transplant Outdoors June 27 Jun 27 – Jul 11
Direct Sow June 20 Jun 20 – Jul 11
Harvest August 22 Aug 22 – Oct 24

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

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 6b

📆 Growing Season

100 days in Klamath County

Growing Tips for Thai Basil in Klamath County

Direct sow Thai Basil outdoors after June 13 in Klamath 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 Klamath County, OR?

Klamath County is in Zone 6b with an average last frost of June 13. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Klamath County, OR?

Klamath County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is June 13 and first fall frost is September 21.

🌱

Your Klamath County Garden Planner — Free

A 24-page printable planner built for Klamath County (Zone 6b). 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 Klamath County, OR. 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.