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When to plant Phlox in Laurel, DE

Aim to plant Phlox in Laurel on or after April 10; the window stays open through May 1. Laurel's 218-day frost-free season gives you enough for a full main crop and a short fall succession.

When to Plant Phlox in Laurel, DE

Sussex County, Delaware Zone 7b July

This month in Sussex County, Delaware

We've pulled the most time-sensitive tasks for Sussex County, Delaware this July and put them front and centre. Tackle them in order.

Avg. last frost April 3
Avg. first frost November 7
Soil temp (4") 87°F
Watering Low
Pest pressure High
Daylight 14.5 hrs
  1. Pick phlox

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

Before August arrives, get these ready
  • First harvests: phlox

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Garden Phlox (Phlox paniculata) is a beloved native perennial of eastern North America, producing large, domed clusters of fragrant flowers atop upright stems from mid-summer into fall. Its sweet honey-like fragrance carries on summer evenings and draws hummingbirds, butterflies, and sphinx moths. Modern cultivars offer colors spanning white, pink, salmon, red, purple, and bicolors. A classic cottage garden stalwart, phlox combines well with black-eyed Susans, echinacea, and ornamental grasses in naturalistic plantings. Select mildew-resistant cultivars for best long-term performance.

Laurel, Delaware is in USDA Zone 7b. The average last spring frost is April 3 and the first fall frost is November 7, giving you a growing season of approximately 218 days.

At an elevation of 1,090 feet, Sussex County receives approximately 46 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Phlox during the growing season.

Perennial Blooms in Summer Pollinator-friendly Good for cutting Fragrant
Laurel, DE (Zone 7b) Long season
218 days
Last Spring Frost April 3
218 growing days
First Fall Frost November 7

Laurel Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.5

Drainage

Well Drained

Phlox Planting Risk Windows

Early Start (70% safe) ✓ Fits season (59 days to spare)
Start indoors: Jan 23 Transplant: Apr 3 🌸 Bloom: Jun 12 – Sep 4
Recommended (50%) ✓ Fits season (57 days to spare)
Start indoors: Jan 30 Transplant: Apr 10 🌸 Bloom: Jun 19 – Sep 11
Safe Start (90%) ✓ Fits season (49 days to spare)
Start indoors: Feb 18 Transplant: Apr 29 🌸 Bloom: Jul 8 – Sep 30

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 Laurel

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

Soil pH

Your soil pH (5.6–6.5) overlaps with Phlox's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Phlox

0.3"
Planting Depth
18"
Between Plants
24"
Between Rows

Succession Planting Phlox

3
successive plantings in your 218-day season

Sow every 9.1 weeks. Last sowing by Jul 20 to harvest before frost.

Phlox Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 221 gal / 100 sq ft

Monthly Watering Guide for Phlox

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

Month Phlox Needs Rainfall You Supplement Action
Jan 3.5" 0" ❄️ Dormant
Feb 3.5" 0" ❄️ Dormant
Mar 3.9" 0" ❄️ Dormant
Apr 4.3" 3.7" 0.6" 💧 Light watering
May 4.3" 4.5" 0" ✅ Rainfall sufficient
Jun 4.3" 3.7" 0.6" 💧 Light watering
Jul 4.3" 5.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.9" 0.4" 💧 Light watering
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 4.3" 3.2" 1.1" 💧 Light watering
Dec 3.3" 0" ❄️ Dormant

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

Phlox 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.

Phlox needs ~1,520 GDD — county provides 3,488 GDD Excellent fit

Phlox Planting Timeline — Laurel, DE

Phlox Planting Calendar

Activity When Date Range
Start Indoors January 30 Jan 30 – Feb 13
Transplant Outdoors April 10 Apr 10 – Apr 24
Direct Sow April 10 Apr 10 – May 1
Bloom June 19 Jun 19 – Sep 11

Plant 0.3" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

80–110 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 7b

📆 Growing Season

218 days in Sussex County

Growing Tips for Phlox in Laurel

Direct sow Phlox outdoors after April 03 in Sussex County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors 8–10 weeks before last frost, or transplant container divisions in spring. Named cultivar seeds may not come true; divisions from named plants are the preferred propagation method. Space generously (18–24 inches) and avoid overhead watering to reduce powdery mildew risk. Good air circulation is critical — thin clumps to the strongest 5–7 stems per plant in spring. Deadhead after the primary bloom flush to encourage secondary flowering. Division every 2–3 years in spring keeps plants vigorous. Fall planting of divisions (Zones 5+) is equally effective. Year 2+ plants develop into full clumps with the most prolific bloom.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

When should I plant Phlox in Laurel, DE?

In Laurel, DE, plant Phlox after the last frost (around April 3) and before the first frost (around November 7). Best results when soil holds above 50°F.

What growing zone is Laurel, DE for Phlox?

Laurel sits in USDA Zone 7b. Phlox grows reliably in zones 3a through 9a, so it's a good fit here.

Can Phlox grow in Laurel's climate?

Yes — Phlox grows well in Laurel's temperate climate. Laurel averages a 218-day frost-free season, with last frost around April 3 and first frost around November 7.

🌱

Your Sussex County Garden Planner — Free

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