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When to plant Basil in McLean County County,

McLean County County gardeners should plant Basil between April 25 and May 16 in spring. With McLean County County's Zone 6a climate (last frost April 18), Basil needs 75 days to mature — plant by August 4 for a full harvest.

When to Plant Basil in McLean County, IL

Basil
McLean County, Illinois Zone 6a June

June in McLean County, Illinois — your action list

Welcome to June in Zone 6a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 18
Avg. first frost October 18
Soil temp (4") 69°F
Watering Low
Pest pressure High
Daylight 14.9 hrs
  1. Start basil indoors

    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.

  2. Pick basil

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

To set up a strong July, finish these tasks
  • First harvests: 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.

McLean County, Illinois is in USDA Zone 6a. The average last spring frost is April 18 and the first fall frost is October 18, giving you a growing season of approximately 183 days.

At an elevation of 1,024 feet, McLean County receives approximately 31.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Basil during the growing season.

McLean County, IL (Zone 6a) Moderate season
183 days
Last Spring Frost April 18
183 growing days
First Fall Frost October 18

McLean County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Basil Planting Risk Windows

Early Start (70% safe) ✓ Fits season (47 days to spare)
Start indoors: Feb 24 Transplant: Apr 28 🍅 Harvest: Jun 23 – Aug 25
Recommended (50%) ✓ Fits season (50 days to spare)
Start indoors: Feb 28 Transplant: May 2 🍅 Harvest: Jun 27 – Aug 29
Safe Start (90%) ✓ Fits season (50 days to spare)
Start indoors: Mar 14 Transplant: May 16 🍅 Harvest: Jul 11 – Sep 12

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 McLean County

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

Soil pH

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

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — Basil will thrive.

How to Plant Basil

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

Succession Planting Basil

4
successive plantings in your 183-day season

Sow every 5.7 weeks. Last sowing by Aug 04 to harvest before frost.

Basil Water Budget

Plant needs
0.6″/week
Rainfall provides
0.7″/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 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 2.6" 2.9" 0" ✅ Rainfall sufficient
May 2.6" 4" 0" ✅ Rainfall sufficient
Jun 2.6" 3.8" 0" ✅ Rainfall sufficient
Jul 2.6" 3.5" 0" ✅ Rainfall sufficient
Aug 2.6" 3.2" 0" ✅ Rainfall sufficient
Sep 2.6" 2.7" 0" ✅ Rainfall sufficient
Oct 2.6" 2.8" 0" ✅ Rainfall sufficient
Nov 2" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in McLean 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 ~906 GDD — county provides 2,653 GDD Excellent fit

Basil Planting Timeline — McLean County, IL

Basil Planting Calendar

Activity When Date Range
Start Indoors February 28 Feb 28 – Mar 14
Transplant Outdoors May 2 May 2 – May 16
Direct Sow April 25 Apr 25 – May 16
Harvest June 27 Jun 27 – Aug 29

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July Harvest
August Harvest
September
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: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

183 days in McLean County

Growing Tips for Basil in McLean County

Direct sow Basil outdoors after April 18 in McLean 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 McLean County, IL?

McLean County is in Zone 6a with an average last frost of April 18. Plan your Basil planting based on this frost date — see the calendar above for exact timing.

What planting zone is McLean County, IL?

McLean County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 18 and first fall frost is October 18.

When should I plant Basil in McLean County County, ?

In McLean County County, , plant Basil after the last frost (around April 18) and before the first frost (around October 18). Best results when soil holds above 50°F.

What growing zone is McLean County County, for Basil?

McLean County County sits in USDA Zone 6a. Basil grows reliably in zones 4a through 11b, so it's a good fit here.

Can Basil grow in McLean County County's climate?

Yes — Basil grows well in McLean County County's temperate climate. McLean County County averages a 183-day frost-free season, with last frost around April 18 and first frost around October 18.

🌱

Your McLean County Garden Planner — Free

A 22-page printable planner built for McLean County (Zone 6a). 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 McLean County, IL. 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.