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When to Plant Thai Basil in Fremont County, WY

Fremont County, Wyoming Zone 5a May

This month in Fremont County, Wyoming

We've pulled the most time-sensitive tasks for Fremont County, Wyoming this May and put them front and centre. Tackle them in order.

Avg. last frost May 15
Avg. first frost September 21
Soil temp (4") 38°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
  1. Move thai basil from tray to bed

    Your last frost (May 15) has passed. These warm-season crops can handle outdoor soil now.

  2. Plant thai basil from seed, right in the garden

    Your soil is 38°F — warm enough for these to germinate without babying.

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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.

Fremont County, Wyoming is in USDA Zone 5a. The average last spring frost is May 15 and the first fall frost is September 21, giving you a growing season of approximately 129 days.

At an elevation of 6,059 feet, Fremont County receives approximately 14.8 inches of rainfall annually with predominantly loam soil. Summer highs average 80°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.

Fremont County, WY (Zone 5a) Short season
129 days
Last Spring Frost May 15
129 growing days
First Fall Frost September 21

Fremont County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 23 Transplant: May 25 🍅 Harvest: Jul 20 – Sep 21
Recommended (50%) ✗ May not fit
Start indoors: Mar 27 Transplant: May 29 🍅 Harvest: Jul 24 – Sep 25
Safe Start (90%) ✗ May not fit
Start indoors: Apr 22 Transplant: Jun 24 🍅 Harvest: Aug 19 – Oct 21

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 Fremont County

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

Soil pH

Your soil pH (6.7–7.8) 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 Fremont 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 moderate (2.4%). 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

2
successive plantings in your 129-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
0.5″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,127 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 4.3" 1.8" 2.5" 🚿 Regular watering
Jun 4.3" 1.2" 3.1" 🚿 Regular watering
Jul 4.3" 1.2" 3.1" 🚿 Regular watering
Aug 4.3" 1.4" 2.9" 🚿 Regular watering
Sep 4.3" 1.3" 3" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 1.2" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Fremont 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 ~625 GDD — county provides 1,290 GDD Excellent fit

Thai Basil Planting Timeline — Fremont County, WY

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 27 Mar 27 – Apr 10
Transplant Outdoors May 29 May 29 – Jun 12
Direct Sow May 22 May 22 – Jun 12
Harvest July 24 Jul 24 – Sep 25

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

129 days in Fremont County

Growing Tips for Thai Basil in Fremont County

Direct sow Thai Basil outdoors after May 15 in Fremont County when soil has warmed and frost danger has passed.

Fremont County receives only 15" 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 →

Frequently Asked Questions

When should I plant Thai Basil in Fremont County, WY?

Fremont County is in Zone 5a with an average last frost of May 15. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Fremont County, WY?

Fremont County, Wyoming is in USDA Hardiness Zone 5a. The average last spring frost is May 15 and first fall frost is September 21.

🌱

Your Fremont County Garden Planner — Free

A 24-page printable planner built for Fremont County (Zone 5a). 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 Fremont County, WY. 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.