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When to Plant Eggplant in Yakima County, WA

Yakima County, Washington Zone 7a May

May in Yakima County, Washington — your action list

Your Yakima County, Washington 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 6
Avg. first frost October 3
Soil temp (4") 54°F
Watering Critical
Pest pressure Low
Daylight 14.8 hrs
  1. Move eggplant from tray to bed

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Direct-sow eggplant

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

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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.

Yakima County, Washington is in USDA Zone 7a. The average last spring frost is May 6 and the first fall frost is October 3, giving you a growing season of approximately 150 days.

At an elevation of 3,150 feet, Yakima County receives approximately 18 inches of rainfall annually with predominantly silt 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.

Yakima County, WA (Zone 7a) Moderate season
150 days
Last Spring Frost May 6
150 growing days
First Fall Frost October 3
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Yakima County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (3 days to spare)
Start indoors: Feb 26 Transplant: May 14 🍅 Harvest: Jul 23 – Sep 24
Recommended (50%) ✓ Fits season (3 days to spare)
Start indoors: Mar 4 Transplant: May 20 🍅 Harvest: Jul 29 – Sep 30
Safe Start (90%) ✓ Fits season (0 days to spare)
Start indoors: Mar 24 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 Yakima County

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

Soil pH

Your soil pH (5.5–6.3) is within Eggplant's preferred range (5.5–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.8%) — Eggplant will thrive.

How to Plant Eggplant

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

Succession Planting Eggplant

2
successive plantings in your 150-day season

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

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 796 gal / 100 sq ft

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 2.6" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 1.6" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 4.8" 1" 3.8" 🚿 Regular watering
Jun 4.8" 0.6" 4.2" 🚿 Regular watering
Jul 4.8" 0.3" 4.5" 🚿 Regular watering
Aug 4.8" 0.3" 4.5" 🚿 Regular watering
Sep 4.8" 0.6" 4.2" 🚿 Regular watering
Oct 4.8" 1.4" 3.4" 🚿 Regular watering
Nov 3.2" 0" ❄️ Dormant
Dec 3.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Yakima 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 2,175 GDD Excellent fit

Eggplant Planting Timeline — Yakima County, WA

Eggplant Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 – Mar 18
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 13 May 13 – Jun 3
Harvest July 29 Jul 29 – Sep 30

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 7a

📆 Growing Season

150 days in Yakima County

Growing Tips for Eggplant in Yakima County

Direct sow Eggplant outdoors after May 06 in Yakima 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.

Yakima County receives only 18" 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 Yakima County, WA?

Yakima County is in Zone 7a with an average last frost of May 6. Plan your Eggplant planting based on this frost date — see the calendar above for exact timing.

What planting zone is Yakima County, WA?

Yakima County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is May 6 and first fall frost is October 3.

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Your Yakima County Garden Planner — Free

A 24-page printable planner built for Yakima County (Zone 7a). 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 Yakima County, WA. 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.