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When to Plant Basil in Sioux County, ND

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.

Sioux County, North Dakota is in USDA Zone 4a. The average last spring frost is May 12 and the first fall frost is October 1, giving you a growing season of approximately 142 days.

At an elevation of 1,012 feet, Sioux County receives approximately 32.3 inches of rainfall annually with predominantly loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Basil to ensure they mature before fall.

Sioux County, ND (Zone 4a) Short season
142 days
Last Spring Frost May 12
142 growing days
First Fall Frost October 1

Sioux County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (2 days to spare)
Start indoors: Mar 9 Transplant: May 25 🍅 Harvest: Jul 20 – Sep 21
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Mar 17 Transplant: Jun 2 🍅 Harvest: Jul 28 – Sep 29
Safe Start (90%) ✓ Fits season (5 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
0.1″/week
Watering frequency Only during dry spells
Season total 68 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Basil needs ~719 GDD — county provides 1,633 GDD Excellent fit

Basil Planting Timeline โ€” Sioux County, ND

Basil Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 โ€“ Mar 31
Transplant Outdoors June 2 Jun 2 โ€“ Jun 16
Direct Sow May 19 May 19 โ€“ Jun 9
Harvest July 28 Jul 28 โ€“ Sep 29

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 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 4a

Growing Season

142 days

Growing Tips for Sioux 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 Sioux County, ND?

Sioux County is in Zone 4a with an average last frost of May 12. Plan your Basil planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Sioux County, ND?

Sioux County, North Dakota is in USDA Hardiness Zone 4a. The average last spring frost is May 12 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

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