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When to Plant Thai Basil in Cheshire County, NH

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.

Cheshire County, New Hampshire is in USDA Zone 5a. The average last spring frost is May 8 and the first fall frost is October 10, giving you a growing season of approximately 155 days.

At an elevation of 708 feet, Cheshire County receives approximately 47 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Thai Basil during the growing season.

Cheshire County, NH (Zone 5a) Moderate season
155 days
Last Spring Frost May 8
155 growing days
First Fall Frost October 10

Cheshire County Soil Profile

Soil Type

Silt Loam

Soil pH

4.8-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Start indoors: Mar 12 Transplant: May 14 🍅 Harvest: Jul 9 – Sep 10
Recommended (50%) ✓ Fits season (22 days to spare)
Start indoors: Mar 20 Transplant: May 22 🍅 Harvest: Jul 17 – Sep 18
Safe Start (90%) ✓ Fits season (25 days to spare)
Start indoors: Mar 30 Transplant: Jun 1 🍅 Harvest: Jul 27 – Sep 28

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
1.3″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thai Basil needs ~906 GDD — county provides 2,247 GDD Excellent fit

Thai Basil Planting Timeline โ€” Cheshire County, NH

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 โ€“ Apr 3
Transplant Outdoors May 22 May 22 โ€“ Jun 5
Direct Sow May 15 May 15 โ€“ Jun 5
Harvest July 17 Jul 17 โ€“ Sep 18

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 Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July Harvest
August Harvest
September Harvest
October โ€”
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

155 days

Growing Tips for Cheshire 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 Cheshire County, NH?

Cheshire County is in Zone 5a with an average last frost of May 8. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Cheshire County, NH?

Cheshire County, New Hampshire is in USDA Hardiness Zone 5a. The average last spring frost is May 8 and first fall frost is October 10.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Cheshire 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 Cheshire County, NH. Local conditions may vary. Last updated: April 2026.