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When to Plant Eggplant in Oconto County, WI

Oconto County, Wisconsin Zone 5a May

This month in Oconto County, Wisconsin

May is a pivotal month for Oconto County, Wisconsin gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost May 9
Avg. first frost October 4
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.7 hrs
  1. Harden off and plant eggplant

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Put eggplant seeds straight in the ground

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

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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.

Oconto County, Wisconsin is in USDA Zone 5a. The average last spring frost is May 9 and the first fall frost is October 4, giving you a growing season of approximately 148 days.

At an elevation of 794 feet, Oconto County receives approximately 37.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Eggplant to ensure they mature before fall.

Oconto County, WI (Zone 5a) Short season
148 days
Last Spring Frost May 9
148 growing days
First Fall Frost October 4

Oconto County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (2 days to spare)
Start indoors: Feb 22 Transplant: May 17 🍅 Harvest: Jul 26 – Sep 27
Recommended (50%) ✓ Fits season (1 days to spare)
Start indoors: Feb 28 Transplant: May 23 🍅 Harvest: Aug 1 – Oct 3
Safe Start (90%) ✓ Fits season (0 days to spare)
Start indoors: Mar 17 Transplant: Jun 9 🍅 Harvest: Aug 18 – Oct 20

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 Oconto County

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

Soil pH

Your soil pH (6.0–7.0) is within Eggplant's preferred range (5.5–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.7%) — Eggplant will thrive.

How to Plant Eggplant

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

Succession Planting Eggplant

2
successive plantings in your 148-day season

Sow every 7.4 weeks. Last sowing by Jul 11 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
1.1″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 52 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 1.6" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 4.8" 4.1" 0.7" 💧 Light watering
Jun 4.8" 4.7" 0.1" 💧 Light watering
Jul 4.8" 4.6" 0.2" 💧 Light watering
Aug 4.8" 4.1" 0.7" 💧 Light watering
Sep 4.8" 3.3" 1.5" 💧 Light watering
Oct 4.8" 2.7" 2.1" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Oconto 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 ~750 GDD — county provides 1,480 GDD Excellent fit

Eggplant Planting Timeline — Oconto County, WI

Eggplant Planting Calendar

Activity When Date Range
Start Indoors February 28 Feb 28 – Mar 14
Transplant Outdoors May 23 May 23 – Jun 6
Direct Sow May 16 May 16 – Jun 6
Harvest August 1 Aug 1 – Oct 3

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · Only during dry spells

📅 Days to Maturity

65–85 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

148 days in Oconto County

Growing Tips for Eggplant in Oconto County

Direct sow Eggplant outdoors after May 09 in Oconto 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 Oconto County, WI?

Oconto County is in Zone 5a with an average last frost of May 9. Plan your Eggplant planting based on this frost date — see the calendar above for exact timing.

What planting zone is Oconto County, WI?

Oconto County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is May 9 and first fall frost is October 4.

🌱

Your Oconto County Garden Planner — Free

A 24-page printable planner built for Oconto County (Zone 5a). 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 Oconto County, WI. 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.