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When to plant Phlox in Crawford County, IL

Plant Phlox in Crawford County after April 14; the prime window is April 21–May 12.

When to Plant Phlox in Crawford County, IL

Crawford County, Illinois Zone 6b July

July to-do list for Crawford County, Illinois

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

Avg. last frost April 14
Avg. first frost October 23
Soil temp (4") 81°F
Watering Moderate
Pest pressure High
Daylight 14.5 hrs
  1. Pick phlox

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

Looking ahead to August
  • 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.

Crawford County, Illinois is in USDA Zone 6b. The average last spring frost is April 14 and the first fall frost is October 23, giving you a growing season of approximately 192 days.

At an elevation of 555 feet, Crawford County receives approximately 33 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Phlox during the growing season.

Perennial Blooms in Summer Pollinator-friendly Good for cutting Fragrant
Crawford County, IL (Zone 6b) Moderate season
192 days
Last Spring Frost April 14
192 growing days
First Fall Frost October 23

Crawford County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-7

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✓ Fits season (32 days to spare)
Start indoors: Feb 3 Transplant: Apr 14 🌸 Bloom: Jun 23 – Sep 15
Recommended (50%) ✓ Fits season (31 days to spare)
Start indoors: Feb 10 Transplant: Apr 21 🌸 Bloom: Jun 30 – Sep 22
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Feb 22 Transplant: May 3 🌸 Bloom: Jul 12 – Oct 4

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 Crawford County

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

Soil pH

Your soil pH (6.3–7.0) is within Phlox's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Phlox.

How to Plant Phlox

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

Succession Planting Phlox

2
successive plantings in your 192-day season

Sow every 9.1 weeks. Last sowing by Jul 05 to harvest before frost.

Phlox Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 570 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 4.3" 3.1" 1.2" 💧 Light watering
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 3.8" 0.5" 💧 Light watering
Jul 4.3" 3.7" 0.6" 💧 Light watering
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 2.7" 1.6" 💧 Light watering
Oct 4.3" 2.5" 1.8" 💧 Light watering
Nov 2.7" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Crawford 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 ~1,662 GDD — county provides 3,360 GDD Excellent fit

Phlox Planting Timeline — Crawford County, IL

Phlox Planting Calendar

Activity When Date Range
Start Indoors February 10 Feb 10 – Feb 24
Transplant Outdoors April 21 Apr 21 – May 5
Direct Sow April 21 Apr 21 – May 12
Bloom June 30 Jun 30 – Sep 22

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 6b

📆 Growing Season

192 days in Crawford County

Growing Tips for Phlox in Crawford County

Direct sow Phlox outdoors after April 14 in Crawford County when soil has warmed and frost danger has passed.

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 Crawford County, IL?

Crawford County is in Zone 6b with an average last frost of April 14. Plan your Phlox planting based on this frost date — see the calendar above for exact timing.

What planting zone is Crawford County, IL?

Crawford County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 14 and first fall frost is October 23.

When should I plant Phlox in Crawford County, IL?

In Crawford County, IL, plant Phlox after the last frost (around April 14) and before the first frost (around October 23). Best results when soil holds above 50°F.

What growing zone is Crawford County, IL for Phlox?

Crawford County sits in USDA Zone 6b. Phlox grows reliably in zones 3a through 9a, so it's a good fit here.

Can Phlox grow in Crawford County's climate?

Yes — Phlox grows well in Crawford County's temperate climate. Crawford County averages a 192-day frost-free season, with last frost around April 14 and first frost around October 23.

🌱

Your Crawford County Garden Planner — Free

A 22-page printable planner built for Crawford 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 Crawford County, IL. 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.