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When to Plant Phlox in Pend Oreille County, WA

Pend Oreille County, Washington Zone 6a July

July to-do list for Pend Oreille County, Washington

Your garden in Pend Oreille County, Washington is working on a schedule, even when you're not. Here's where you should be this July.

Avg. last frost May 10
Avg. first frost September 23
Soil temp (4") 67°F
Watering Critical
Pest pressure High
Daylight 15.5 hrs
  1. Begin indoor sowing: phlox

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

  2. Harvest phlox as they ripen

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

Coming up in August — start thinking about
  • First harvests: phlox

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Garden Phlox (Phlox paniculata) is a beloved native perennial of eastern North America, producing large, domed clusters of fragrant flowers atop upright stems from mid-summer into fall. Its sweet honey-like fragrance carries on summer evenings and draws hummingbirds, butterflies, and sphinx moths. Modern cultivars offer colors spanning white, pink, salmon, red, purple, and bicolors. A classic cottage garden stalwart, phlox combines well with black-eyed Susans, echinacea, and ornamental grasses in naturalistic plantings. Select mildew-resistant cultivars for best long-term performance.

Pend Oreille County, Washington is in USDA Zone 6a. The average last spring frost is May 10 and the first fall frost is September 23, giving you a growing season of approximately 136 days.

At an elevation of 3,807 feet, Pend Oreille County receives approximately 13.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Phlox during the growing season. With low rainfall, drip irrigation is essential for growing Phlox successfully. Mulch heavily to conserve soil moisture.

Perennial Blooms in Summer Pollinator-friendly Good for cutting Fragrant
Pend Oreille County, WA (Zone 6a) Short season
136 days
Last Spring Frost May 10
136 growing days
First Fall Frost September 23

Pend Oreille County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.6

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 27 Transplant: May 8 🌸 Bloom: Jul 17 – Oct 9
Recommended (50%) ✗ May not fit
Start indoors: Mar 8 Transplant: May 17 🌸 Bloom: Jul 26 – Oct 18
Safe Start (90%) ✗ May not fit
Start indoors: Mar 29 Transplant: Jun 7 🌸 Bloom: Aug 16 – Nov 8

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 Pend Oreille County

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

Soil pH

Your soil pH (5.3–6.6) is more acidic than Phlox prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Phlox.

Organic Matter

Organic matter is excellent (5.0%) — Phlox will thrive.

How to Plant Phlox

0.3"
Planting Depth
18"
Between Plants
24"
Between Rows

Phlox Water Budget

Plant needs
1.0″/week
Rainfall provides
0.4″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,080 gal / 100 sq ft

Monthly Watering Guide for Phlox

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

Month Phlox Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 0.9" 0" ❄️ Dormant
May 4.3" 0.8" 3.5" 🚿 Regular watering
Jun 4.3" 0.5" 3.8" 🚿 Regular watering
Jul 4.3" 0.2" 4.1" 🚿 Regular watering
Aug 4.3" 0.2" 4.1" 🚿 Regular watering
Sep 4.3" 0.6" 3.7" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 2.1" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Phlox 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.

Phlox needs ~1,378 GDD — county provides 1,972 GDD Excellent fit

Phlox Planting Timeline — Pend Oreille County, WA

Phlox Planting Calendar

Activity When Date Range
Start Indoors March 8 Mar 8 – Mar 22
Transplant Outdoors May 17 May 17 – May 31
Direct Sow May 17 May 17 – Jun 7
Bloom July 26 Jul 26 – Oct 18

Plant 0.3" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

80–110 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6a

📆 Growing Season

136 days in Pend Oreille County

Growing Tips for Phlox in Pend Oreille County

Direct sow Phlox outdoors after May 10 in Pend Oreille County when soil has warmed and frost danger has passed.

Pend Oreille County receives only 13" of rain annually. Phlox 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, or transplant container divisions in spring. Named cultivar seeds may not come true; divisions from named plants are the preferred propagation method. Space generously (18–24 inches) and avoid overhead watering to reduce powdery mildew risk. Good air circulation is critical — thin clumps to the strongest 5–7 stems per plant in spring. Deadhead after the primary bloom flush to encourage secondary flowering. Division every 2–3 years in spring keeps plants vigorous. Fall planting of divisions (Zones 5+) is equally effective. Year 2+ plants develop into full clumps with the most prolific bloom.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Phlox in Pend Oreille County, WA?

Pend Oreille County is in Zone 6a with an average last frost of May 10. Plan your Phlox planting based on this frost date — see the calendar above for exact timing.

What planting zone is Pend Oreille County, WA?

Pend Oreille County, Washington is in USDA Hardiness Zone 6a. The average last spring frost is May 10 and first fall frost is September 23.

🌱

Your Pend Oreille County Garden Planner — Free

A 22-page printable planner built for Pend Oreille County (Zone 6a). 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 Pend Oreille 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.