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When to Plant Phlox in Bastrop County, TX

Bastrop County, Texas Zone 9a July

July in Bastrop County, Texas — your action list

July rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Bastrop County, Texas.

Avg. last frost February 27
Avg. first frost December 1
Soil temp (4") 80°F
Watering Low
Pest pressure High
Daylight 13.8 hrs

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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.

Bastrop County, Texas is in USDA Zone 9a. The average last spring frost is February 27 and the first fall frost is December 1, giving you a growing season of approximately 277 days.

At an elevation of 3,716 feet, Bastrop County receives approximately 57 inches of rainfall annually with predominantly clay soil. Summer highs average 91°F, providing good warmth for Phlox during the growing season. Clay soil retains moisture well for Phlox, but amend with compost to improve drainage and prevent root rot. 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
Bastrop County, TX (Zone 9a) Year-round
277 days
Last Spring Frost February 27
277 growing days
First Fall Frost December 1

Bastrop County Soil Profile

Soil Type

Clay

Soil pH

7.2-7.9

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✓ Fits season (167 days to spare)
Start indoors: Dec 19 Transplant: Jan 30 🌸 Bloom: Apr 10 – Jun 5
Recommended (50%) ✓ Fits season (165 days to spare)
Start indoors: Jan 2 Transplant: Feb 13 🌸 Bloom: Apr 24 – Jun 19
Safe Start (90%) ✓ Fits season (154 days to spare)
Start indoors: Jan 25 Transplant: Mar 8 🌸 Bloom: May 17 – Jul 12

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 Bastrop County

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

Soil pH

Your soil pH (7.2–7.9) is more alkaline than Phlox prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Heavy clay soil (47% clay) in Bastrop County compacts easily and drains slowly. Amend with compost and avoid working soil when wet.

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Phlox.

How to Plant Phlox

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

Succession Planting Phlox

4
successive plantings in your 277-day season

Sow every 9.1 weeks. Last sowing by Aug 13 to harvest before frost.

Phlox Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 412 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 1.5" 0" ❄️ Dormant
Feb 4.3" 2.1" 2.2" 🚿 Regular watering
Mar 4.3" 4.1" 0.2" 💧 Light watering
Apr 4.3" 6.1" 0" ✅ Rainfall sufficient
May 4.3" 8.8" 0" ✅ Rainfall sufficient
Jun 4.3" 9.4" 0" ✅ Rainfall sufficient
Jul 4.3" 6.7" 0" ✅ Rainfall sufficient
Aug 4.3" 5.8" 0" ✅ Rainfall sufficient
Sep 4.3" 5.6" 0" ✅ Rainfall sufficient
Oct 4.3" 3.5" 0.8" 💧 Light watering
Nov 4.3" 1.9" 2.4" 🚿 Regular watering
Dec 4.3" 1.5" 2.8" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in Bastrop 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 ~1,734 GDD — county provides 5,073 GDD Excellent fit

Phlox Planting Timeline — Bastrop County, TX

Phlox Planting Calendar

Activity When Date Range
Start Indoors January 2 Jan 2 – Jan 16
Transplant Outdoors February 13 Feb 13 – Feb 27
Direct Sow February 13 Feb 13 – Mar 6
Bloom April 24 Apr 24 – Jun 19

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 9a

📆 Growing Season

277 days in Bastrop County

Growing Tips for Phlox in Bastrop County

Direct sow Phlox outdoors after February 27 in Bastrop County when soil has warmed and frost danger has passed.

With Bastrop County's clay soil (47% clay), work in 3-4 inches of compost before planting Phlox. Avoid tilling when soil is wet to prevent compaction.

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 Bastrop County, TX?

Bastrop County is in Zone 9a with an average last frost of February 27. Plan your Phlox planting based on this frost date — see the calendar above for exact timing.

What planting zone is Bastrop County, TX?

Bastrop County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 27 and first fall frost is December 1.

🌱

Your Bastrop County Garden Planner — Free

A 22-page printable planner built for Bastrop County (Zone 9a). 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 Bastrop 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.