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When to plant Petunia in Lyon County, MN

Plant Petunia in Lyon County during the brief May 11–May 25 window. With 151 frost-free days, fall plantings can't mature before October 2.

When to Plant Petunia in Lyon County, MN

Lyon County, Minnesota Zone 5a July

This month in Lyon County, Minnesota

Welcome to July in Zone 5a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 4
Avg. first frost October 2
Soil temp (4") 71°F
Watering Moderate
Pest pressure High
Daylight 15 hrs
  1. Harvest petunia as they ripen

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Get ahead of August
  • 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.

Lyon County, Minnesota is in USDA Zone 5a. The average last spring frost is May 4 and the first fall frost is October 2, giving you a growing season of approximately 151 days.

At an elevation of 634 feet, Lyon County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Petunia to ensure they mature before fall.

Annual Blooms in Summer Pollinator-friendly Fragrant
Lyon County, MN (Zone 5a) Moderate season
151 days
Last Spring Frost May 4
151 growing days
First Fall Frost October 2

Lyon County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.2

Drainage

Well Drained

Petunia Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 3 Transplant: May 5 🌸 Bloom: Jul 14 – Oct 6
Recommended (50%) ✗ May not fit
Start indoors: Mar 9 Transplant: May 11 🌸 Bloom: Jul 20 – Oct 12
Safe Start (90%) ✗ May not fit
Start indoors: Mar 20 Transplant: May 22 🌸 Bloom: Jul 31 – Oct 23

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 Lyon County

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

Soil pH

Your soil pH (5.8–7.2) overlaps with Petunia's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — Petunia will thrive.

How to Plant Petunia

12"
Between Plants
12"
Between Rows

Succession Planting Petunia

2
successive plantings in your 151-day season

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

Petunia Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
Watering frequency Only during dry spells
Season total 2 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 1.6" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 4.3" 4.5" 0" ✅ Rainfall sufficient
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Lyon 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 ~920 GDD — county provides 1,736 GDD Excellent fit

Petunia Planting Timeline — Lyon County, MN

Petunia Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors May 11 May 11 – May 25
Bloom July 20 Jul 20 – Oct 12

· 12" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

151 days in Lyon County

Growing Tips for Petunia in Lyon County

Direct sow Petunia outdoors after May 04 in Lyon 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 Lyon County, MN?

Lyon County is in Zone 5a with an average last frost of May 4. Plan your Petunia planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lyon County, MN?

Lyon County, Minnesota is in USDA Hardiness Zone 5a. The average last spring frost is May 4 and first fall frost is October 2.

When should I plant Petunia in Lyon County, MN?

In Lyon County, MN, plant Petunia after the last frost (around May 4) and before the first frost (around October 2). Best results when soil holds above 50°F.

What growing zone is Lyon County, MN for Petunia?

Lyon County sits in USDA Zone 5a. Petunia grows reliably in zones 2a through 11b, so it's a good fit here.

Can Petunia grow in Lyon County's climate?

Yes — Petunia grows well in Lyon County's temperate climate. Lyon County averages a 151-day frost-free season, with last frost around May 4 and first frost around October 2.

🌱

Your Lyon County Garden Planner — Free

A 22-page printable planner built for Lyon County (Zone 5a). 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 Lyon County, MN. Local conditions may vary. Last updated: July 2026.

Sources & credits

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