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When to plant Eggplant in Bonner County, ID

Bonner County gardeners should plant Eggplant between May 12 and June 2 in spring. With Bonner County's Zone 6b climate (last frost May 5), Eggplant needs 65–85 days to mature — plant by July 10 for a full harvest.

When to Plant Eggplant in Bonner County, ID

Eggplant
Bonner County, Idaho Zone 6b June

Your June gardening checklist

Your garden in Bonner County, Idaho is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost May 5
Avg. first frost October 3
Soil temp (4") 45°F
Watering Critical
Pest pressure High
Daylight 15.8 hrs
July prep starts now
  • Starting indoors: eggplant
  • 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.

Bonner County, Idaho is in USDA Zone 6b. The average last spring frost is May 5 and the first fall frost is October 3, giving you a growing season of approximately 151 days.

At an elevation of 7,480 feet, Bonner County receives approximately 12.9 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Eggplant during the growing season. With low rainfall, drip irrigation is essential for growing Eggplant successfully. Mulch heavily to conserve soil moisture.

Bonner County, ID (Zone 6b) Moderate season
151 days
Last Spring Frost May 5
151 growing days
First Fall Frost October 3

Bonner County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.2

Drainage

Well Drained

Eggplant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 17 Transplant: May 12 🍅 Harvest: Jul 21 – Sep 22
Recommended (50%) ✓ Fits season (4 days to spare)
Start indoors: Feb 24 Transplant: May 19 🍅 Harvest: Jul 28 – Sep 29
Safe Start (90%) ✗ May not fit
Start indoors: Mar 23 Transplant: Jun 15 🍅 Harvest: Aug 24 – Oct 26

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 Bonner County

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

Soil pH

Your soil pH (6.4–8.2) is more alkaline than Eggplant prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Eggplant.

How to Plant Eggplant

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

Succession Planting Eggplant

2
successive plantings in your 151-day season

Sow every 7.4 weeks. Last sowing by Jul 10 to harvest before frost.

Eggplant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.4″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,195 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 0.9" 0" ❄️ Dormant
Feb 0.7" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.5" 0" ❄️ Dormant
May 4.8" 1.5" 3.3" 🚿 Regular watering
Jun 4.8" 0.9" 3.9" 🚿 Regular watering
Jul 4.8" 1.1" 3.7" 🚿 Regular watering
Aug 4.8" 1.2" 3.6" 🚿 Regular watering
Sep 4.8" 1.1" 3.7" 🚿 Regular watering
Oct 4.8" 1.1" 3.7" 🚿 Regular watering
Nov 0.9" 0" ❄️ Dormant
Dec 0.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Bonner 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 ~1,088 GDD — county provides 2,189 GDD Excellent fit

Eggplant Planting Timeline — Bonner County, ID

Eggplant Planting Calendar

Activity When Date Range
Start Indoors February 24 Feb 24 – Mar 10
Transplant Outdoors May 19 May 19 – Jun 2
Direct Sow May 12 May 12 – Jun 2
Harvest July 28 Jul 28 – Sep 29

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 Harvest
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · 2-3 times/week

📅 Days to Maturity

65–85 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 6b

📆 Growing Season

151 days in Bonner County

Growing Tips for Eggplant in Bonner County

Direct sow Eggplant outdoors after May 05 in Bonner 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.

Bonner County receives only 13" of rain annually. Eggplant needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Bonner County, ID?

Bonner County is in Zone 6b with an average last frost of May 5. Plan your Eggplant planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bonner County, ID?

Bonner County, Idaho is in USDA Hardiness Zone 6b. The average last spring frost is May 5 and first fall frost is October 3.

When should I plant Eggplant in Bonner County, ID?

In Bonner County, ID, plant Eggplant after the last frost (around May 5) and before the first frost (around October 3). Best results when soil holds above 50°F.

What growing zone is Bonner County, ID for Eggplant?

Bonner 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 Bonner County's climate?

Yes — Eggplant grows well in Bonner County's temperate climate. Bonner County averages a 151-day frost-free season, with last frost around May 5 and first frost around October 3.

🌱

Your Bonner County Garden Planner — Free

A 22-page printable planner built for Bonner 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 Bonner County, ID. 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.