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When to Plant Thai Basil in Jackson County, MN

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.

Jackson County, Minnesota is in USDA Zone 4b. The average last spring frost is April 30 and the first fall frost is October 6, giving you a growing season of approximately 159 days.

At an elevation of 1,042 feet, Jackson County receives approximately 37.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Thai Basil to ensure they mature before fall.

Jackson County, MN (Zone 4b) Moderate season
159 days
Last Spring Frost April 30
159 growing days
First Fall Frost October 6

Jackson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (23 days to spare)
Start indoors: Feb 25 Transplant: May 13 🍅 Harvest: Jul 8 – Sep 9
Recommended (50%) ✓ Fits season (19 days to spare)
Start indoors: Mar 5 Transplant: May 21 🍅 Harvest: Jul 16 – Sep 17
Safe Start (90%) ✓ Fits season (20 days to spare)
Start indoors: Mar 19 Transplant: Jun 4 🍅 Harvest: Jul 30 – Oct 1

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.

Soil Compatibility in Jackson County

How your county's soil matches Thai Basil's growing requirements.

Soil pH

Your soil pH (6.1โ€“7.0) is within Thai Basil's preferred range (6.0โ€“7.0).

Soil Texture

The silt loam soil in Jackson County is excellent for Thai Basil โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.2%) โ€” Thai Basil will thrive.

How to Plant Thai Basil

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Thai Basil

3
successive plantings in your 159-day season

Sow every 5.7 weeks. Last sowing by Jul 23 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 10 gal / 100 sq ft

Monthly Watering Guide for Thai Basil

Thai Basil needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Thai Basil Needs Rainfall You Supplement Action
Jan โ€” 1.6" 0" โ„๏ธ Dormant
Feb โ€” 1.5" 0" โ„๏ธ Dormant
Mar โ€” 2.3" 0" โ„๏ธ Dormant
Apr 4.3" 3.5" 0.8" ๐Ÿ’ง Light watering
May 4.3" 4.6" 0" โœ… Rainfall sufficient
Jun 4.3" 4.7" 0" โœ… Rainfall sufficient
Jul 4.3" 4.5" 0" โœ… Rainfall sufficient
Aug 4.3" 3.6" 0.7" ๐Ÿ’ง Light watering
Sep 4.3" 3.2" 1.1" ๐Ÿ’ง Light watering
Oct 4.3" 3.1" 1.2" ๐Ÿ’ง Light watering
Nov โ€” 2.9" 0" โ„๏ธ Dormant
Dec โ€” 2" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Aprโ€“Oct in Jackson County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Thai Basil Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" โ€” every day above 50ยฐF deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Thai Basil needs ~625 GDD — county provides 1,590 GDD Excellent fit

Thai Basil Planting Timeline โ€” Jackson County, MN

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 5 Mar 5 โ€“ Mar 19
Transplant Outdoors May 21 May 21 โ€“ Jun 4
Direct Sow May 7 May 7 โ€“ May 28
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 โ€”
May Transplant Outdoors Direct Sow
June Transplant Outdoors
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท Only during dry spells

๐Ÿ“… Days to Maturity

50โ€“75 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 4b

๐Ÿ“† Growing Season

159 days in Jackson County

Growing Tips for Thai Basil in Jackson County

Direct sow Thai Basil outdoors after April 30 in Jackson County when soil has warmed and frost danger has passed.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Thai Basil in Jackson County, MN?

Jackson County is in Zone 4b with an average last frost of April 30. Plan your Thai Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Jackson County, MN?

Jackson County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is April 30 and first fall frost is October 6.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Jackson County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Jackson County, MN. Local conditions may vary. Last updated: April 2026.