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When to plant Phlox in Morgan County County,

Morgan County County sits in USDA Zone 6a. Plant Phlox between April 21 (after last frost on April 14) and May 12.

When to Plant Phlox in Morgan County, IL

Morgan County, Illinois Zone 6a June

What to do in June

Your Morgan County, Illinois garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.

Avg. last frost April 14
Avg. first frost October 17
Soil temp (4") 68°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
  1. Get phlox seeds going inside

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

  2. Harvest phlox as they ripen

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

A few tasks this June that'll pay off in July
  • 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.

Morgan County, Illinois is in USDA Zone 6a. The average last spring frost is April 14 and the first fall frost is October 17, giving you a growing season of approximately 186 days.

At an elevation of 1,348 feet, Morgan County receives approximately 39.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Phlox during the growing season.

Perennial Blooms in Summer Pollinator-friendly Good for cutting Fragrant
Morgan County, IL (Zone 6a) Moderate season
186 days
Last Spring Frost April 14
186 growing days
First Fall Frost October 17

Morgan County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.2

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Start indoors: Feb 5 Transplant: Apr 16 🌸 Bloom: Jun 25 – Sep 17
Recommended (50%) ✓ Fits season (25 days to spare)
Start indoors: Feb 10 Transplant: Apr 21 🌸 Bloom: Jun 30 – Sep 22
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Feb 27 Transplant: May 8 🌸 Bloom: Jul 17 – Oct 9

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 Morgan County

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

Soil pH

Your soil pH (6.1–7.2) overlaps with Phlox's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — Phlox will thrive.

How to Plant Phlox

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

Succession Planting Phlox

2
successive plantings in your 186-day season

Sow every 9.1 weeks. Last sowing by Jun 29 to harvest before frost.

Phlox Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 233 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 1.7" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 4.3" 4.1" 0.2" 💧 Light watering
May 4.3" 4.9" 0" ✅ Rainfall sufficient
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 4.4" 0" ✅ Rainfall sufficient
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 3.7" 0.6" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Morgan 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 2,697 GDD Excellent fit

Phlox Planting Timeline — Morgan 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 · Only during dry spells

📅 Days to Maturity

80–110 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

186 days in Morgan County

Growing Tips for Phlox in Morgan County

Direct sow Phlox outdoors after April 14 in Morgan 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 Morgan County, IL?

Morgan County is in Zone 6a 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 Morgan County, IL?

Morgan County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 14 and first fall frost is October 17.

When should I plant Phlox in Morgan County County, ?

In Morgan County County, , plant Phlox after the last frost (around April 14) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Morgan County County, for Phlox?

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

Can Phlox grow in Morgan County County's climate?

Yes — Phlox grows well in Morgan County County's temperate climate. Morgan County County averages a 186-day frost-free season, with last frost around April 14 and first frost around October 17.

🌱

Your Morgan County Garden Planner — Free

A 22-page printable planner built for Morgan 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 Morgan County, IL. Local conditions may vary. Last updated: June 2026.

Sources & credits

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