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When to Plant Thai Basil in Moffat County, CO

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.

Moffat County, Colorado is in USDA Zone 5a. The average last spring frost is June 7 and the first fall frost is September 14, giving you a growing season of approximately 99 days.

At an elevation of 6,597 feet, Moffat County receives approximately 12.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Thai Basil during the growing season. With low rainfall, drip irrigation is essential for growing Thai Basil successfully. Mulch heavily to conserve soil moisture.

Moffat County, CO (Zone 5a) Very short season
99 days
Last Spring Frost June 7
99 growing days
First Fall Frost September 14

Moffat County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 9 Transplant: Jun 11 🍅 Harvest: Aug 6 – Oct 8
Recommended (50%) ✗ May not fit
Start indoors: Apr 19 Transplant: Jun 21 🍅 Harvest: Aug 16 – Oct 18
Safe Start (90%) ✗ May not fit
Start indoors: May 2 Transplant: Jul 4 🍅 Harvest: Aug 29 – Oct 31

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
0.5″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 823 gal / 100 sq ft
Drought risk

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

Thai Basil needs ~906 GDD — county provides 1,435 GDD Excellent fit

Thai Basil Planting Timeline โ€” Moffat County, CO

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors April 19 Apr 19 โ€“ May 3
Transplant Outdoors June 21 Jun 21 โ€“ Jul 5
Direct Sow June 14 Jun 14 โ€“ Jul 5
Harvest August 16 Aug 16 โ€“ Oct 18

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Start Indoors
June Transplant Outdoors Direct Sow
July Transplant Outdoors Direct Sow
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 5a

Growing Season

99 days

Growing Tips for Moffat 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 Moffat County, CO?

Moffat County is in Zone 5a with an average last frost of June 7. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Moffat County, CO?

Moffat County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 7 and first fall frost is September 14.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Moffat County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

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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 Moffat County, CO. Local conditions may vary. Last updated: April 2026.