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When to plant Phlox in Bartholomew County County,

The best window to plant Phlox in Bartholomew County County, is April 19–May 10, when soil warms to 50°F. Last frost typically hits April 12; first frost October 20.

When to Plant Phlox in Bartholomew County, IN

Bartholomew County, Indiana Zone 6b June

June in Bartholomew County, Indiana — your action list

Each item below is timed to Bartholomew County, Indiana's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost April 12
Avg. first frost October 20
Soil temp (4") 71°F
Watering Low
Pest pressure High
Daylight 14.7 hrs
  1. Start phlox indoors

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

  2. Basket week: phlox

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

July will be here before you know it — start on
  • 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.

Bartholomew County, Indiana is in USDA Zone 6b. The average last spring frost is April 12 and the first fall frost is October 20, giving you a growing season of approximately 191 days.

At an elevation of 1,376 feet, Bartholomew County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Phlox during the growing season.

Perennial Blooms in Summer Pollinator-friendly Good for cutting Fragrant
Bartholomew County, IN (Zone 6b) Moderate season
191 days
Last Spring Frost April 12
191 growing days
First Fall Frost October 20
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Bartholomew County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✓ Fits season (31 days to spare)
Start indoors: Feb 4 Transplant: Apr 15 🌸 Bloom: Jun 24 – Sep 16
Recommended (50%) ✓ Fits season (30 days to spare)
Start indoors: Feb 8 Transplant: Apr 19 🌸 Bloom: Jun 28 – Sep 20
Safe Start (90%) ✓ Fits season (22 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 Bartholomew County

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

Soil pH

Your soil pH (6.2–7.0) is within Phlox's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — 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 191-day season

Sow every 9.1 weeks. Last sowing by Jul 02 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 179 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" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 4.3" 4" 0.3" 💧 Light watering
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.3" 0" ✅ Rainfall sufficient
Sep 4.3" 3.4" 0.9" 💧 Light watering
Oct 4.3" 3.5" 0.8" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Bartholomew 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 ~1,591 GDD — county provides 3,199 GDD Excellent fit

Phlox Planting Timeline — Bartholomew County, IN

Phlox Planting Calendar

Activity When Date Range
Start Indoors February 8 Feb 8 – Feb 22
Transplant Outdoors April 19 Apr 19 – May 3
Direct Sow April 19 Apr 19 – May 10
Bloom June 28 Jun 28 – Sep 20

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
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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: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

191 days in Bartholomew County

Growing Tips for Phlox in Bartholomew County

Direct sow Phlox outdoors after April 12 in Bartholomew 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 Bartholomew County, IN?

Bartholomew County is in Zone 6b with an average last frost of April 12. Plan your Phlox planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bartholomew County, IN?

Bartholomew County, Indiana is in USDA Hardiness Zone 6b. The average last spring frost is April 12 and first fall frost is October 20.

When should I plant Phlox in Bartholomew County, ?

In Bartholomew County, , plant Phlox after the last frost (around April 12) and before the first frost (around October 20). Best results when soil holds above 50°F.

What growing zone is Bartholomew County, for Phlox?

Bartholomew 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 Bartholomew County's climate?

Yes — Phlox grows well in Bartholomew County's temperate climate. Bartholomew County averages a 191-day frost-free season, with last frost around April 12 and first frost around October 20.

🌱

Your Bartholomew County Garden Planner — Free

A 22-page printable planner built for Bartholomew 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 Bartholomew County, IN. 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.