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When to Plant Petunia in Pacific County, WA

Pacific County, Washington Zone 9a July

This month in Pacific County, Washington

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

Avg. last frost April 18
Avg. first frost October 29
Soil temp (4") 90°F
Watering Critical
Pest pressure High
Daylight 15.3 hrs
  1. Pick petunia

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Looking ahead to August
  • First harvests: petunia

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Petunias (Petunia x hybrida) are warm-season tender annuals prized for their prolific, trumpet-shaped blooms in nearly every color. They perform from hanging baskets to garden borders and bloom continuously from late spring until frost, provided spent flowers are removed regularly.

Pacific County, Washington is in USDA Zone 9a. The average last spring frost is April 18 and the first fall frost is October 29, giving you a growing season of approximately 194 days.

At an elevation of 14 feet, Pacific County receives approximately 47.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Petunia during the growing season.

Annual Blooms in Summer Pollinator-friendly Fragrant
Pacific County, WA (Zone 9a) Moderate season
194 days
Last Spring Frost April 18
194 growing days
First Fall Frost October 29

Pacific County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.2

Drainage

Well Drained

Petunia Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 8 Transplant: Mar 22 🌸 Bloom: May 31 – Nov 1
Recommended (50%) ✗ May not fit
Start indoors: Feb 21 Transplant: Apr 4 🌸 Bloom: Jun 13 – Nov 14
Safe Start (90%) ✗ May not fit
Start indoors: Mar 14 Transplant: Apr 25 🌸 Bloom: Jul 4 – Dec 5

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 Pacific County

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

Soil pH

Your soil pH (5.6–6.2) is more acidic than Petunia prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.5%) — Petunia will thrive.

How to Plant Petunia

12"
Between Plants
12"
Between Rows

Succession Planting Petunia

3
successive plantings in your 194-day season

Sow every 8 weeks. Last sowing by Jul 31 to harvest before frost.

Petunia Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Petunia

Petunia needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Petunia Needs Rainfall You Supplement Action
Jan 7.2" 0" ❄️ Dormant
Feb 5" 0" ❄️ Dormant
Mar 4.5" 0" ❄️ Dormant
Apr 4.3" 3.8" 0.5" 💧 Light watering
May 4.3" 2.8" 1.5" 💧 Light watering
Jun 4.3" 1.8" 2.5" 🚿 Regular watering
Jul 4.3" 0.9" 3.4" 🚿 Regular watering
Aug 4.3" 0.9" 3.4" 🚿 Regular watering
Sep 4.3" 1.7" 2.6" 🚿 Regular watering
Oct 4.3" 4.2" 0.1" 💧 Light watering
Nov 8" 0" ❄️ Dormant
Dec 6.7" 0" ❄️ Dormant

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

Petunia 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.

Petunia needs ~1,160 GDD — county provides 2,813 GDD Excellent fit

Petunia Planting Timeline — Pacific County, WA

Petunia Planting Calendar

Activity When Date Range
Start Indoors February 21 Feb 21 – Mar 7
Transplant Outdoors April 4 Apr 4 – Apr 18
Bloom June 13 Jun 13 – Nov 14

· 12" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

194 days in Pacific County

Growing Tips for Petunia in Pacific County

Direct sow Petunia outdoors after April 18 in Pacific County when soil has warmed and frost danger has passed.

Common pests for Petunia 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; seeds need light to germinate — press onto moist mix surface, do not cover. Transplant after last frost once nights stay above 50°F. Pinch back leggy plants mid-summer to encourage bushy re-bloom. Wave/spreading types tolerate light shade but bloom less. Feed every 2 weeks with balanced fertilizer once established.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Petunia in Pacific County, WA?

Pacific County is in Zone 9a with an average last frost of April 18. Plan your Petunia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pacific County, WA?

Pacific County, Washington is in USDA Hardiness Zone 9a. The average last spring frost is April 18 and first fall frost is October 29.

🌱

Your Pacific County Garden Planner — Free

A 22-page printable planner built for Pacific County (Zone 9a). 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 Pacific County, WA. 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.