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When to Plant Thai Basil in Niobrara County, WY

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.

Niobrara County, Wyoming is in USDA Zone 4b. 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 5,262 feet, Niobrara County receives approximately 19.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82ยฐF, 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.

Niobrara County, WY (Zone 4b) Short season
129 days
Last Spring Frost May 15
129 growing days
First Fall Frost September 21

Niobrara County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 18 Transplant: Jun 3 🍅 Harvest: Jul 29 – Sep 30
Recommended (50%) ✗ May not fit
Start indoors: Mar 20 Transplant: Jun 5 🍅 Harvest: Jul 31 – Oct 2
Safe Start (90%) ✗ May not fit
Start indoors: Apr 9 Transplant: Jun 25 🍅 Harvest: Aug 20 – Oct 22

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 503 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Thai Basil needs ~719 GDD — county provides 1,483 GDD Excellent fit

Thai Basil Planting Timeline โ€” Niobrara County, WY

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 โ€“ Apr 3
Transplant Outdoors June 5 Jun 5 โ€“ Jun 19
Direct Sow May 22 May 22 โ€“ Jun 12
Harvest July 31 Jul 31 โ€“ Oct 2

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

50โ€“75 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4b

Growing Season

129 days

Growing Tips for Niobrara County

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

Level Up Your Garden

Frequently Asked Questions

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

Niobrara County is in Zone 4b with an average last frost of May 15. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Niobrara County, WY?

Niobrara County, Wyoming is in USDA Hardiness Zone 4b. The average last spring frost is May 15 and first fall frost is September 21.

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Plan Your Garden with Confidence

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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 Niobrara County, WY. Local conditions may vary. Last updated: April 2026.