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When to plant Petunia in Macon County County,

Macon County County sits in cold Zone 6a. Plant Petunia April 20–May 4 for the single annual harvest; the October 19 first frost closes the window.

When to Plant Petunia in Macon County, IL

Macon County, Illinois Zone 6a June

Your June gardening checklist

Your garden in Macon County, Illinois is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost April 13
Avg. first frost October 19
Soil temp (4") 70°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
  1. Start petunia indoors

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

  2. Bring in the petunia

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

Looking ahead to 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.

Macon County, Illinois is in USDA Zone 6a. The average last spring frost is April 13 and the first fall frost is October 19, giving you a growing season of approximately 189 days.

At an elevation of 1,064 feet, Macon County receives approximately 31.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Petunia during the growing season.

Annual Blooms in Summer Pollinator-friendly Fragrant
Macon County, IL (Zone 6a) Moderate season
189 days
Last Spring Frost April 13
189 growing days
First Fall Frost October 19

Macon County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.1

Drainage

Well Drained

Petunia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (14 days to spare)
Start indoors: Feb 10 Transplant: Apr 14 🌸 Bloom: Jun 23 – Sep 29
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Feb 16 Transplant: Apr 20 🌸 Bloom: Jun 29 – Oct 5
Safe Start (90%) ✓ Fits season (17 days to spare)
Start indoors: Feb 27 Transplant: May 1 🌸 Bloom: Jul 10 – Oct 16

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 Macon County

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

Soil pH

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

Soil Texture

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

Organic Matter

Organic matter is excellent (4.3%) — Petunia will thrive.

How to Plant Petunia

12"
Between Plants
12"
Between Rows

Succession Planting Petunia

3
successive plantings in your 189-day season

Sow every 8 weeks. Last sowing by Jul 21 to harvest before frost.

Petunia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 512 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 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 4.3" 2.9" 1.4" 💧 Light watering
May 4.3" 3.1" 1.2" 💧 Light watering
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 3.5" 0.8" 💧 Light watering
Aug 4.3" 3.5" 0.8" 💧 Light watering
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Macon 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 ~1,160 GDD — county provides 2,740 GDD Excellent fit

Petunia Planting Timeline — Macon County, IL

Petunia Planting Calendar

Activity When Date Range
Start Indoors February 16 Feb 16 – Mar 2
Transplant Outdoors April 20 Apr 20 – May 4
Bloom June 29 Jun 29 – Oct 5

· 12" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Transplant Outdoors
May Transplant Outdoors
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 6a

📆 Growing Season

189 days in Macon County

Growing Tips for Petunia in Macon County

Direct sow Petunia outdoors after April 13 in Macon 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 Macon County, IL?

Macon County is in Zone 6a with an average last frost of April 13. Plan your Petunia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Macon County, IL?

Macon County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 13 and first fall frost is October 19.

When should I plant Petunia in Macon County County, ?

In Macon County County, , plant Petunia after the last frost (around April 13) and before the first frost (around October 19). Best results when soil holds above 50°F.

What growing zone is Macon County County, for Petunia?

Macon County County sits in USDA Zone 6a. Petunia grows reliably in zones 2a through 11b, so it's a good fit here.

Can Petunia grow in Macon County County's climate?

Yes — Petunia grows well in Macon County County's temperate climate. Macon County County averages a 189-day frost-free season, with last frost around April 13 and first frost around October 19.

🌱

Your Macon County Garden Planner — Free

A 22-page printable planner built for Macon County (Zone 6a). 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 Macon County, IL. 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.