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When to Plant Basil in Benton County, MN

Basil is a fragrant warm-season herb essential to Italian and Thai cuisines. It comes in many varieties including sweet, Thai, purple, and lemon types.

Benton County, Minnesota is in USDA Zone 4a. The average last spring frost is May 2 and the first fall frost is October 6, giving you a growing season of approximately 157 days.

At an elevation of 1,178 feet, Benton County receives approximately 39 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Basil to ensure they mature before fall.

Benton County, MN (Zone 4a) Moderate season
157 days
Last Spring Frost May 2
157 growing days
First Fall Frost October 6

Benton County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (16 days to spare)
Start indoors: Mar 1 Transplant: May 17 🍅 Harvest: Jul 12 – Sep 13
Recommended (50%) ✓ Fits season (17 days to spare)
Start indoors: Mar 7 Transplant: May 23 🍅 Harvest: Jul 18 – Sep 19
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: Mar 24 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
1.0″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 359 gal / 100 sq ft
Basil needs ~812 GDD — county provides 2,041 GDD Excellent fit

Basil Planting Timeline โ€” Benton County, MN

Basil Planting Calendar

Activity When Date Range
Start Indoors March 7 Mar 7 โ€“ Mar 21
Transplant Outdoors May 23 May 23 โ€“ Jun 6
Direct Sow May 9 May 9 โ€“ May 30
Harvest July 18 Jul 18 โ€“ Sep 19

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

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 4a

Growing Season

157 days

Growing Tips for Benton County

Start seeds indoors or direct sow after last frost. Pinch flower buds to extend leaf production. Harvest leaves from the top down, cutting just above a leaf pair.

Companion Planting

Good Companions

Avoid Planting Near

  • Rue
  • Sage

Level Up Your Garden

๐ŸŒพ Save Your Own Basil Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let flower spikes dry brown on the plant.
Storage Store airtight; viable 5 years at 35ยฐF, under 45% humidity.

Isolate 150 ft between varieties. Different basil species can cross.

Frequently Asked Questions

When should I plant Basil in Benton County, MN?

Benton County is in Zone 4a with an average last frost of May 2. Plan your Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Benton County, MN?

Benton County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 2 and first fall frost is October 6.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Benton County gardeners in Zone 4a 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 Benton County, MN. Local conditions may vary. Last updated: April 2026.