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When to Plant Thai Basil in Door County, WI

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.

Door County, Wisconsin is in USDA Zone 5a. The average last spring frost is May 11 and the first fall frost is October 8, giving you a growing season of approximately 150 days.

At an elevation of 564 feet, Door County receives approximately 41.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Thai Basil during the growing season.

Door County, WI (Zone 5a) Moderate season
150 days
Last Spring Frost May 11
150 growing days
First Fall Frost October 8

Door County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (18 days to spare)
Start indoors: Mar 17 Transplant: May 19 🍅 Harvest: Jul 14 – Sep 15
Recommended (50%) ✓ Fits season (17 days to spare)
Start indoors: Mar 23 Transplant: May 25 🍅 Harvest: Jul 20 – Sep 21
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Apr 7 Transplant: Jun 9 🍅 Harvest: Aug 4 – Oct 6

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
1.2″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 208 gal / 100 sq ft
Drought risk

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

Thai Basil needs ~953 GDD — county provides 2,287 GDD Excellent fit

Thai Basil Planting Timeline โ€” Door County, WI

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 โ€“ Apr 6
Transplant Outdoors May 25 May 25 โ€“ Jun 8
Direct Sow May 18 May 18 โ€“ Jun 8
Harvest July 20 Jul 20 โ€“ Sep 21

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

150 days

Growing Tips for Door 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 Door County, WI?

Door County is in Zone 5a with an average last frost of May 11. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Door County, WI?

Door County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is May 11 and first fall frost is October 8.

๐ŸŒฑ

Plan Your Garden with Confidence

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