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When to plant Petunia in Bear, DE

Plant Petunia in Bear during the brief April 6–April 20 window. With 208 frost-free days, fall plantings can't mature before October 31.

When to Plant Petunia in Bear, DE

New Castle County, Delaware Zone 7b August

What to do in August

A quick August briefing for New Castle County, Delaware gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 6
Avg. first frost October 31
Soil temp (4") 85°F
Watering Moderate
Pest pressure High
Daylight 13.6 hrs
  1. Harvest petunia as they ripen

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

A few tasks this August that'll pay off in September
  • 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.

Bear, Delaware is in USDA Zone 7b. The average last spring frost is April 6 and the first fall frost is October 31, giving you a growing season of approximately 208 days.

At an elevation of 415 feet, New Castle County receives approximately 38.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 89°F, providing good warmth for Petunia during the growing season.

Annual Blooms in Summer Pollinator-friendly Fragrant
Bear, DE (Zone 7b) Long season
208 days
Last Spring Frost April 6
208 growing days
First Fall Frost October 31

Bear Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-7.1

Drainage

Well Drained

Petunia Planting Risk Windows

Early Start (70% safe) ✓ Fits season (22 days to spare)
Start indoors: Jan 31 Transplant: Mar 28 🌸 Bloom: Jun 6 – Oct 3
Recommended (50%) ✓ Fits season (19 days to spare)
Start indoors: Feb 9 Transplant: Apr 6 🌸 Bloom: Jun 15 – Oct 12
Safe Start (90%) ✓ Fits season (7 days to spare)
Start indoors: Mar 5 Transplant: Apr 30 🌸 Bloom: Jul 9 – Nov 5

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 Bear

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

Soil pH

Your soil pH (5.2–7.1) overlaps with Petunia's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Petunia

12"
Between Plants
12"
Between Rows

Succession Planting Petunia

3
successive plantings in your 208-day season

Sow every 8 weeks. Last sowing by Aug 02 to harvest before frost.

Petunia Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 427 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 2.4" 0" ❄️ Dormant
Feb 2.7" 0" ❄️ Dormant
Mar 3.4" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 3.3" 1" 💧 Light watering
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 3.2" 1.1" 💧 Light watering
Sep 4.3" 3.1" 1.2" 💧 Light watering
Oct 4.3" 3.2" 1.1" 💧 Light watering
Nov 3.4" 0" ❄️ Dormant
Dec 2.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in New Castle 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 ~1,340 GDD — county provides 3,484 GDD Excellent fit

Petunia Planting Timeline — Bear, DE

Petunia Planting Calendar

Activity When Date Range
Start Indoors February 9 Feb 9 – Feb 23
Transplant Outdoors April 6 Apr 6 – Apr 20
Bloom June 15 Jun 15 – Oct 12

· 12" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March
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 · Only during dry spells

📅 Days to Maturity

70–90 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 7b

📆 Growing Season

208 days in New Castle County

Growing Tips for Petunia in Bear

Direct sow Petunia outdoors after April 06 in New Castle 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 →

When should I plant Petunia in Bear, DE?

In Bear, DE, plant Petunia after the last frost (around April 6) and before the first frost (around October 31). Best results when soil holds above 50°F.

What growing zone is Bear, DE for Petunia?

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

Can Petunia grow in Bear's climate?

Yes — Petunia grows well in Bear's temperate climate. Bear averages a 208-day frost-free season, with last frost around April 6 and first frost around October 31.

🌱

Your New Castle County Garden Planner — Free

A 22-page printable planner built for New Castle 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 New Castle County, DE. Local conditions may vary. Last updated: August 2026.