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When to Plant Phlox in Baker County, OR

Baker County, Oregon Zone 6b August

Baker County, Oregon gardeners: here's your August plan

Your garden in Baker County, Oregon is working on a schedule, even when you're not. Here's where you should be this August.

Avg. last frost May 30
Avg. first frost September 12
Soil temp (4") 76°F
Watering Critical
Pest pressure High
Daylight 13.9 hrs
  1. Get phlox seeds going inside

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

  2. Start harvesting phlox

    If you can't use it all right away, check the food-preservation section of your planner.

Get ahead of September
  • 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.

Baker County, Oregon is in USDA Zone 6b. The average last spring frost is May 30 and the first fall frost is September 12, giving you a growing season of approximately 105 days.

At an elevation of 1,398 feet, Baker County receives approximately 16.9 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
Baker County, OR (Zone 6b) Short season
105 days
Last Spring Frost May 30
105 growing days
First Fall Frost September 12

Baker County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.5

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 17 Transplant: May 26 🌸 Bloom: Aug 4 – Oct 27
Recommended (50%) ✗ May not fit
Start indoors: Mar 28 Transplant: Jun 6 🌸 Bloom: Aug 15 – Nov 7
Safe Start (90%) ✗ May not fit
Start indoors: Apr 17 Transplant: Jun 26 🌸 Bloom: Sep 4 – Nov 27

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 Baker County

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

Soil pH

Your soil pH (5.3–6.5) is more acidic than Phlox prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Baker 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 (4.8%) — 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
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 583 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 2.3" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.1" 0" ❄️ Dormant
May 4.3" 1.1" 3.2" 🚿 Regular watering
Jun 4.3" 0.6" 3.7" 🚿 Regular watering
Jul 4.3" 0.2" 4.1" 🚿 Regular watering
Aug 4.3" 0.3" 4" 🚿 Regular watering
Sep 4.3" 0.8" 3.5" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 2.5" 0" ❄️ Dormant
Dec 3.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Baker 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 1,522 GDD Good fit

Phlox Planting Timeline — Baker County, OR

Phlox Planting Calendar

Activity When Date Range
Start Indoors March 28 Mar 28 – Apr 11
Transplant Outdoors June 6 Jun 6 – Jun 20
Direct Sow June 6 Jun 6 – Jun 27
Bloom August 15 Aug 15 – Nov 7

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

80–110 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6b

📆 Growing Season

105 days in Baker County

Growing Tips for Phlox in Baker County

Direct sow Phlox outdoors after May 30 in Baker County when soil has warmed and frost danger has passed.

Your 105.0-day growing season in Baker County is tight for Phlox (80.0-110.0 days to maturity). Start indoors and choose early-maturing varieties.

Baker County receives only 17" 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 Baker County, OR?

Baker County is in Zone 6b with an average last frost of May 30. Plan your Phlox planting based on this frost date — see the calendar above for exact timing.

What planting zone is Baker County, OR?

Baker County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is May 30 and first fall frost is September 12.

🌱

Your Baker County Garden Planner — Free

A 22-page printable planner built for Baker 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 Baker County, OR. Local conditions may vary. Last updated: August 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.