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When to Plant Petunia in Mills County, TX

Mills County, Texas Zone 8b June

June in Mills County, Texas — your action list

We've pulled the most time-sensitive tasks for Mills County, Texas this June and put them front and centre. Tackle them in order.

Avg. last frost March 23
Avg. first frost November 12
Soil temp (4") 71°F
Watering Low
Pest pressure High
Daylight 14 hrs
  1. Harvest petunia as they ripen

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

A few tasks this June that'll pay off in July
  • First harvests: petunia

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Petunias (Petunia x hybrida) are warm-season tender annuals prized for their prolific, trumpet-shaped blooms in nearly every color. They perform from hanging baskets to garden borders and bloom continuously from late spring until frost, provided spent flowers are removed regularly.

Mills County, Texas is in USDA Zone 8b. The average last spring frost is March 23 and the first fall frost is November 12, giving you a growing season of approximately 234 days.

At an elevation of 4,208 feet, Mills County receives approximately 61.7 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Petunia during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Petunia root diseases.

Annual Blooms in Summer Pollinator-friendly Fragrant
Mills County, TX (Zone 8b) Long season
234 days
Last Spring Frost March 23
234 growing days
First Fall Frost November 12
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Mills County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.6

Drainage

Well Drained

Petunia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Jan 15 Transplant: Mar 5 🌸 Bloom: May 14 – Oct 1
Recommended (50%) ✓ Fits season (31 days to spare)
Start indoors: Jan 26 Transplant: Mar 16 🌸 Bloom: May 25 – Oct 12
Safe Start (90%) ✓ Fits season (28 days to spare)
Start indoors: Feb 17 Transplant: Apr 7 🌸 Bloom: Jun 16 – Nov 3

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 Mills County

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

Soil pH

Your soil pH (6.7–7.6) is more alkaline than Petunia prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Petunia.

How to Plant Petunia

12"
Between Plants
12"
Between Rows

Succession Planting Petunia

3
successive plantings in your 234-day season

Sow every 8 weeks. Last sowing by Aug 14 to harvest before frost.

Petunia Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Petunia

Petunia needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Petunia Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 2.4" 0" ❄️ Dormant
Mar 4.3" 3.8" 0.5" 💧 Light watering
Apr 4.3" 6.2" 0" ✅ Rainfall sufficient
May 4.3" 10.5" 0" ✅ Rainfall sufficient
Jun 4.3" 9.5" 0" ✅ Rainfall sufficient
Jul 4.3" 7.5" 0" ✅ Rainfall sufficient
Aug 4.3" 7" 0" ✅ Rainfall sufficient
Sep 4.3" 5.6" 0" ✅ Rainfall sufficient
Oct 4.3" 4.2" 0.1" 💧 Light watering
Nov 4.3" 2" 2.3" 🚿 Regular watering
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Mills County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Petunia 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.

Petunia needs ~1,400 GDD — county provides 4,095 GDD Excellent fit

Petunia Planting Timeline — Mills County, TX

Petunia Planting Calendar

Activity When Date Range
Start Indoors January 26 Jan 26 – Feb 9
Transplant Outdoors March 16 Mar 16 – Mar 30
Bloom May 25 May 25 – Oct 12

· 12" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 8b

📆 Growing Season

234 days in Mills County

Growing Tips for Petunia in Mills County

Direct sow Petunia outdoors after March 23 in Mills County when soil has warmed and frost danger has passed.

Common pests for Petunia in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 8–10 weeks before last frost; seeds need light to germinate — press onto moist mix surface, do not cover. Transplant after last frost once nights stay above 50°F. Pinch back leggy plants mid-summer to encourage bushy re-bloom. Wave/spreading types tolerate light shade but bloom less. Feed every 2 weeks with balanced fertilizer once established.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Petunia in Mills County, TX?

Mills County is in Zone 8b with an average last frost of March 23. Plan your Petunia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mills County, TX?

Mills County, Texas is in USDA Hardiness Zone 8b. The average last spring frost is March 23 and first fall frost is November 12.

🌱

Your Mills County Garden Planner — Free

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