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When to Plant Basil in Campbell County, SD

Campbell County, South Dakota Zone 4b May

May in Campbell County, South Dakota — your action list

Your Campbell County, South Dakota garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.

Avg. last frost May 11
Avg. first frost September 30
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 14.7 hrs
  1. Scatter basil into prepared beds

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

To set up a strong June, finish these tasks
  • Transplants going out: basil

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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.

Campbell County, South Dakota is in USDA Zone 4b. The average last spring frost is May 11 and the first fall frost is September 30, giving you a growing season of approximately 142 days.

At an elevation of 830 feet, Campbell County receives approximately 27.1 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Basil to ensure they mature before fall.

Campbell County, SD (Zone 4b) Short season
142 days
Last Spring Frost May 11
142 growing days
First Fall Frost September 30

Campbell County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (4 days to spare)
Start indoors: Mar 7 Transplant: May 23 🍅 Harvest: Jul 18 – Sep 19
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Mar 16 Transplant: Jun 1 🍅 Harvest: Jul 27 – Sep 28
Safe Start (90%) ✓ Fits season (4 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.

Soil Compatibility in Campbell County

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

Soil pH

Your soil pH (6.5–7.5) overlaps with Basil's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.8%). Annual compost additions will help Basil.

How to Plant Basil

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

Succession Planting Basil

3
successive plantings in your 142-day season

Sow every 5.7 weeks. Last sowing by Jul 17 to harvest before frost.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Basil

Basil needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Basil Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 2.8" 0" ❄️ Dormant
May 2.6" 2.8" 0" ✅ Rainfall sufficient
Jun 2.6" 2" 0.6" 💧 Light watering
Jul 2.6" 2.2" 0.4" 💧 Light watering
Aug 2.6" 2.5" 0.1" 💧 Light watering
Sep 2.6" 2.4" 0.2" 💧 Light watering
Oct 2.5" 0" ❄️ Dormant
Nov 2.1" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Campbell County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

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.

Basil needs ~625 GDD — county provides 1,420 GDD Excellent fit

Basil Planting Timeline — Campbell County, SD

Basil Planting Calendar

Activity When Date Range
Start Indoors March 16 Mar 16 – Mar 30
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 18 May 18 – Jun 8
Harvest July 27 Jul 27 – Sep 28

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

50–75 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

142 days in Campbell County

Growing Tips for Basil in Campbell County

Direct sow Basil outdoors after May 11 in Campbell County when soil has warmed and frost danger has passed.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

🌾 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 35°F, under 45% humidity.

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

Frequently Asked Questions

When should I plant Basil in Campbell County, SD?

Campbell County is in Zone 4b with an average last frost of May 11. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Campbell County, SD?

Campbell County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 11 and first fall frost is September 30.

🌱

Your Campbell County Garden Planner — Free

A 24-page printable planner built for Campbell 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.

Instant PDF download. No spam, unsubscribe any time.

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

Sources & credits

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