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When to Plant Phlox in Concho County, TX

Concho County, Texas Zone 8a July

Your July gardening checklist

Here's what deserves your attention in Concho County, Texas this month. Everything below is tailored to Zone 8a and timed around your local frost dates.

Avg. last frost March 25
Avg. first frost November 12
Soil temp (4") 79°F
Watering Low
Pest pressure High
Daylight 13.9 hrs
  1. Harvest phlox as they ripen

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

Before August arrives, get these ready
  • 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.

Concho County, Texas is in USDA Zone 8a. The average last spring frost is March 25 and the first fall frost is November 12, giving you a growing season of approximately 232 days.

At an elevation of 3,848 feet, Concho County receives approximately 58.2 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Phlox during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Phlox root diseases.

Perennial Blooms in Summer Pollinator-friendly Good for cutting Fragrant
Concho County, TX (Zone 8a) Long season
232 days
Last Spring Frost March 25
232 growing days
First Fall Frost November 12

Concho County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.4

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✓ Fits season (99 days to spare)
Start indoors: Jan 15 Transplant: Mar 12 🌸 Bloom: May 21 – Jul 30
Recommended (50%) ✓ Fits season (92 days to spare)
Start indoors: Jan 28 Transplant: Mar 25 🌸 Bloom: Jun 3 – Aug 12
Safe Start (90%) ✓ Fits season (92 days to spare)
Start indoors: Feb 16 Transplant: Apr 13 🌸 Bloom: Jun 22 – Aug 31

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 Concho County

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

Soil pH

Your soil pH (6.6–7.4) overlaps with Phlox's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.0%). Annual compost additions will help Phlox.

How to Plant Phlox

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

Succession Planting Phlox

3
successive plantings in your 232-day season

Sow every 9.1 weeks. Last sowing by Jul 25 to harvest before frost.

Phlox Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 2.2" 0" ❄️ Dormant
Mar 4.3" 3.4" 0.9" 💧 Light watering
Apr 4.3" 6.8" 0" ✅ Rainfall sufficient
May 4.3" 8.9" 0" ✅ Rainfall sufficient
Jun 4.3" 9.3" 0" ✅ Rainfall sufficient
Jul 4.3" 6.8" 0" ✅ Rainfall sufficient
Aug 4.3" 6.5" 0" ✅ Rainfall sufficient
Sep 4.3" 5.4" 0" ✅ Rainfall sufficient
Oct 4.3" 3.6" 0.7" 💧 Light watering
Nov 4.3" 2.2" 2.1" 💧 Light watering
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Concho 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 ~1,876 GDD — county provides 4,582 GDD Excellent fit

Phlox Planting Timeline — Concho County, TX

Phlox Planting Calendar

Activity When Date Range
Start Indoors January 28 Jan 28 – Feb 11
Transplant Outdoors March 25 Mar 25 – Apr 8
Direct Sow March 25 Mar 25 – Apr 15
Bloom June 3 Jun 3 – Aug 12

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

80–110 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 8a

📆 Growing Season

232 days in Concho County

Growing Tips for Phlox in Concho County

Direct sow Phlox outdoors after March 25 in Concho 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 Concho County, TX?

Concho County is in Zone 8a with an average last frost of March 25. Plan your Phlox planting based on this frost date — see the calendar above for exact timing.

What planting zone is Concho County, TX?

Concho County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 25 and first fall frost is November 12.

🌱

Your Concho County Garden Planner — Free

A 22-page printable planner built for Concho County (Zone 8a). 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 Concho County, TX. 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.