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When to plant Petunia in Dunklin County, MO

Dunklin County sits in cold Zone 7b. Plant Petunia March 27–April 10 for the single annual harvest; the November 2 first frost closes the window.

When to Plant Petunia in Dunklin County, MO

Dunklin County, Missouri Zone 7b August

August in Dunklin County, Missouri — your action list

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

Avg. last frost March 27
Avg. first frost November 2
Soil temp (4") 86°F
Watering Moderate
Pest pressure High
Daylight 13.4 hrs
  1. Bring in the petunia

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

Coming up in September — start thinking about
  • 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.

Dunklin County, Missouri is in USDA Zone 7b. The average last spring frost is March 27 and the first fall frost is November 2, giving you a growing season of approximately 220 days.

At an elevation of 1,344 feet, Dunklin County receives approximately 33.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 94°F, providing good warmth for Petunia during the growing season.

Annual Blooms in Summer Pollinator-friendly Fragrant
Dunklin County, MO (Zone 7b) Long season
220 days
Last Spring Frost March 27
220 growing days
First Fall Frost November 2

Dunklin County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-7.1

Drainage

Well Drained

Petunia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Jan 22 Transplant: Mar 19 🌸 Bloom: May 28 – Sep 24
Recommended (50%) ✓ Fits season (31 days to spare)
Start indoors: Jan 30 Transplant: Mar 27 🌸 Bloom: Jun 5 – Oct 2
Safe Start (90%) ✓ Fits season (31 days to spare)
Start indoors: Feb 19 Transplant: Apr 16 🌸 Bloom: Jun 25 – Oct 22

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 Dunklin County

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

Soil pH

Your soil pH (5.6–7.1) overlaps with Petunia's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Petunia.

How to Plant Petunia

12"
Between Plants
12"
Between Rows

Succession Planting Petunia

3
successive plantings in your 220-day season

Sow every 8 weeks. Last sowing by Aug 04 to harvest before frost.

Petunia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 706 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 1.4" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 4.3" 2.4" 1.9" 💧 Light watering
Apr 4.3" 2.8" 1.5" 💧 Light watering
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 3.7" 0.6" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 2.8" 1.5" 💧 Light watering
Nov 4.3" 2.4" 1.9" 💧 Light watering
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Dunklin 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 ~1,640 GDD — county provides 4,510 GDD Excellent fit

Petunia Planting Timeline — Dunklin County, MO

Petunia Planting Calendar

Activity When Date Range
Start Indoors January 30 Jan 30 – Feb 13
Transplant Outdoors March 27 Mar 27 – Apr 10
Bloom June 5 Jun 5 – Oct 2

· 12" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 7b

📆 Growing Season

220 days in Dunklin County

Growing Tips for Petunia in Dunklin County

Direct sow Petunia outdoors after March 27 in Dunklin 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 Dunklin County, MO?

Dunklin County is in Zone 7b with an average last frost of March 27. Plan your Petunia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dunklin County, MO?

Dunklin County, Missouri is in USDA Hardiness Zone 7b. The average last spring frost is March 27 and first fall frost is November 2.

When should I plant Petunia in Dunklin County, MO?

In Dunklin County, MO, plant Petunia after the last frost (around March 27) and before the first frost (around November 2). Best results when soil holds above 50°F.

What growing zone is Dunklin County, MO for Petunia?

Dunklin County sits in USDA Zone 7b. Petunia grows reliably in zones 2a through 11b, so it's a good fit here.

Can Petunia grow in Dunklin County's climate?

Yes — Petunia grows well in Dunklin County's temperate climate. Dunklin County averages a 220-day frost-free season, with last frost around March 27 and first frost around November 2.

🌱

Your Dunklin County Garden Planner — Free

A 22-page printable planner built for Dunklin County (Zone 7b). 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 Dunklin County, MO. Local conditions may vary. Last updated: August 2026.

Sources & credits

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