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When to plant Eggplant in Jefferson County, IL

The best window to plant Eggplant in Jefferson County, is April 16–May 7, when soil warms to 50°F. Last frost typically hits April 9; first frost October 20.

When to Plant Eggplant in Jefferson County, IL

Eggplant
Jefferson County, Illinois Zone 6b July

July in Jefferson County, Illinois — your action list

Your Jefferson County, Illinois garden is entering a new phase. Here's what's on the schedule for July and why each task matters now.

Avg. last frost April 9
Avg. first frost October 20
Soil temp (4") 81°F
Watering Low
Pest pressure High
Daylight 14.4 hrs
  1. Bring in the eggplant

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

To set up a strong August, finish these tasks
  • First harvests: eggplant

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Eggplant is a heat-loving solanaceous crop that produces glossy fruits in purple, white, or striped varieties. It requires long, warm growing seasons for best production.

Jefferson County, Illinois is in USDA Zone 6b. The average last spring frost is April 9 and the first fall frost is October 20, giving you a growing season of approximately 194 days.

At an elevation of 509 feet, Jefferson County receives approximately 34 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Eggplant during the growing season.

Jefferson County, IL (Zone 6b) Moderate season
194 days
Last Spring Frost April 9
194 growing days
First Fall Frost October 20

Jefferson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.1

Drainage

Well Drained

Eggplant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (45 days to spare)
Start indoors: Jan 24 Transplant: Apr 18 🍅 Harvest: Jun 27 – Aug 29
Recommended (50%) ✓ Fits season (47 days to spare)
Start indoors: Jan 29 Transplant: Apr 23 🍅 Harvest: Jul 2 – Sep 3
Safe Start (90%) ✓ Fits season (50 days to spare)
Start indoors: Feb 8 Transplant: May 3 🍅 Harvest: Jul 12 – Sep 13

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 Jefferson County

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

Soil pH

Your soil pH (6.1–7.1) overlaps with Eggplant's range (5.5–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) — Eggplant will thrive.

How to Plant Eggplant

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Eggplant

3
successive plantings in your 194-day season

Sow every 7.4 weeks. Last sowing by Jul 27 to harvest before frost.

Eggplant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 754 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Eggplant

Eggplant needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Eggplant Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.8" 3.2" 1.6" 💧 Light watering
May 4.8" 4.3" 0.5" 💧 Light watering
Jun 4.8" 3.9" 0.9" 💧 Light watering
Jul 4.8" 3.8" 1" 💧 Light watering
Aug 4.8" 3.4" 1.4" 💧 Light watering
Sep 4.8" 3" 1.8" 💧 Light watering
Oct 4.8" 2.9" 1.9" 💧 Light watering
Nov 2.3" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Eggplant 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.

Eggplant needs ~1,200 GDD — county provides 3,104 GDD Excellent fit

Eggplant Planting Timeline — Jefferson County, IL

Eggplant Planting Calendar

Activity When Date Range
Start Indoors January 29 Jan 29 – Feb 12
Transplant Outdoors April 23 Apr 23 – May 7
Direct Sow April 16 Apr 16 – May 7
Harvest July 2 Jul 2 – Sep 3

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · 1-2 times/week

📅 Days to Maturity

65–85 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

194 days in Jefferson County

Growing Tips for Eggplant in Jefferson County

Direct sow Eggplant outdoors after April 09 in Jefferson County when soil has warmed and frost danger has passed.

Common pests for Eggplant in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 8-10 weeks before last frost. Transplant only after nighttime temperatures stay above 55F. Mulch to retain moisture and warmth around roots.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel
  • Kohlrabi

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Eggplant in Jefferson County, IL?

Jefferson County is in Zone 6b with an average last frost of April 9. Plan your Eggplant planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jefferson County, IL?

Jefferson County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 9 and first fall frost is October 20.

When should I plant Eggplant in Jefferson County, IL?

In Jefferson County, IL, plant Eggplant after the last frost (around April 9) and before the first frost (around October 20). Best results when soil holds above 50°F.

What growing zone is Jefferson County, IL for Eggplant?

Jefferson County sits in USDA Zone 6b. Eggplant grows reliably in zones 5a through 11b, so it's a good fit here.

Can Eggplant grow in Jefferson County's climate?

Yes — Eggplant grows well in Jefferson County's temperate climate. Jefferson County averages a 194-day frost-free season, with last frost around April 9 and first frost around October 20.

🌱

Your Jefferson County Garden Planner — Free

A 22-page printable planner built for Jefferson County (Zone 6b). 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 Jefferson County, IL. Local conditions may vary. Last updated: July 2026.

Sources & credits

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