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When to Plant Thai Basil in Oswego County, NY

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.

Oswego County, New York is in USDA Zone 5a. The average last spring frost is May 7 and the first fall frost is October 11, giving you a growing season of approximately 157 days.

At an elevation of 109 feet, Oswego County receives approximately 38.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Thai Basil during the growing season.

Oswego County, NY (Zone 5a) Moderate season
157 days
Last Spring Frost May 7
157 growing days
First Fall Frost October 11

Oswego County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (25 days to spare)
Start indoors: Mar 11 Transplant: May 13 🍅 Harvest: Jul 8 – Sep 9
Recommended (50%) ✓ Fits season (24 days to spare)
Start indoors: Mar 19 Transplant: May 21 🍅 Harvest: Jul 16 – Sep 17
Safe Start (90%) ✓ Fits season (30 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
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thai Basil needs ~953 GDD — county provides 2,394 GDD Excellent fit

Thai Basil Planting Timeline โ€” Oswego County, NY

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 โ€“ Apr 2
Transplant Outdoors May 21 May 21 โ€“ Jun 4
Direct Sow May 14 May 14 โ€“ Jun 4
Harvest July 16 Jul 16 โ€“ Sep 17

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

157 days

Growing Tips for Oswego 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 Oswego County, NY?

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

What planting zone is Oswego County, NY?

Oswego County, New York is in USDA Hardiness Zone 5a. The average last spring frost is May 7 and first fall frost is October 11.

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Plan Your Garden with Confidence

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