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When to plant Thai Basil in Grant County County,

Grant County County sits in USDA Zone 4b. Plant Thai Basil between May 8 (after last frost on May 1) and May 29.

When to Plant Thai Basil in Grant County, MN

Grant County, Minnesota Zone 4b June

Your June game plan for Grant County, Minnesota

A quick June briefing for Grant County, Minnesota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 1
Avg. first frost October 7
Soil temp (4") 65°F
Watering Low
Pest pressure High
Daylight 15.5 hrs
  1. Begin indoor sowing: thai basil

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

Get ahead of July
  • First harvests: thai basil

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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.

Grant County, Minnesota is in USDA Zone 4b. The average last spring frost is May 1 and the first fall frost is October 7, giving you a growing season of approximately 159 days.

At an elevation of 1,371 feet, Grant County receives approximately 31.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Thai Basil to ensure they mature before fall.

Grant County, MN (Zone 4b) Moderate season
159 days
Last Spring Frost May 1
159 growing days
First Fall Frost October 7
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Grant County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.8

Drainage

Well Drained

Thai Basil Planting Risk Windows

Early Start (70% safe) ✓ Fits season (21 days to spare)
Start indoors: Feb 28 Transplant: May 16 🍅 Harvest: Jul 11 – Sep 12
Recommended (50%) ✓ Fits season (19 days to spare)
Start indoors: Mar 6 Transplant: May 22 🍅 Harvest: Jul 17 – Sep 18
Safe Start (90%) ✓ Fits season (19 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 Grant County

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

Soil pH

Your soil pH (6.1–6.8) is within Thai Basil's preferred range (6.0–7.0).

Soil Texture

The silt loam soil in Grant County is excellent for Thai Basil — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Thai Basil.

Organic Matter

Organic matter is moderate (4.0%). Annual compost additions will help Thai Basil.

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 24 to harvest before frost.

Thai Basil Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 799 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.8" 0" ❄️ Dormant
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 3.7" 0.6" 💧 Light watering
Aug 4.3" 2.9" 1.4" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 2.1" 2.2" 🚿 Regular watering
Nov 1.9" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Grant County). Supplement amounts are based on average rainfall — 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" — every day above 50°F 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 ~766 GDD — county provides 1,947 GDD Excellent fit

Thai Basil Planting Timeline — Grant County, MN

Thai Basil Planting Calendar

Activity When Date Range
Start Indoors March 6 Mar 6 – Mar 20
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 8 May 8 – May 29
Harvest July 17 Jul 17 – Sep 18

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April
May Transplant Outdoors Direct Sow
June Transplant Outdoors
July Harvest
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

159 days in Grant County

Growing Tips for Thai Basil in Grant County

Direct sow Thai Basil outdoors after May 01 in Grant 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 Grant County, MN?

Grant County is in Zone 4b with an average last frost of May 1. Plan your Thai Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Grant County, MN?

Grant County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is May 1 and first fall frost is October 7.

When should I plant Thai Basil in Grant County, ?

In Grant County, , plant Thai Basil after the last frost (around May 1) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Grant County, for Thai Basil?

Grant County sits in USDA Zone 4b. Thai Basil grows reliably in zones 4a through 11b, so it's a good fit here.

Can Thai Basil grow in Grant County's climate?

Yes — Thai Basil grows well in Grant County's temperate climate. Grant County averages a 159-day frost-free season, with last frost around May 1 and first frost around October 7.

🌱

Your Grant County Garden Planner — Free

A 22-page printable planner built for Grant County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Grant County, MN. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.