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When to Plant Watermelon in Jefferson Parish, LA

Jefferson Parish, Louisiana Zone 9b May

May in Jefferson Parish, Louisiana — your action list

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Jefferson Parish, Louisiana.

Avg. last frost January 27
Avg. first frost December 18
Soil temp (4") 76°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Collect watermelon at their peak

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

A few tasks this May that'll pay off in June
  • First harvests: watermelon

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Watermelon is a sprawling vine crop that produces sweet, juicy fruits in hot weather. Varieties range from personal-sized icebox types to 50-pound giants.

Jefferson Parish, Louisiana is in USDA Zone 9b. The average last spring frost is January 27 and the first fall frost is December 18, giving you a growing season of approximately 325 days.

At an elevation of 314 feet, Jefferson Parish receives approximately 55.2 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 100°F, so Watermelon may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Watermelon will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Watermelon root diseases.

Jefferson Parish, LA (Zone 9b) Year-round
325 days
Last Spring Frost January 27
325 growing days
First Fall Frost December 18
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Jefferson Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

5-6.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (196 days to spare)
Start indoors: Dec 23 Transplant: Jan 27 🍅 Harvest: Apr 7 – May 26
Recommended (50%) ✓ Fits season (199 days to spare)
Start indoors: Dec 30 Transplant: Feb 3 🍅 Harvest: Apr 14 – Jun 2
Safe Start (90%) ✓ Fits season (170 days to spare)
Start indoors: Feb 4 Transplant: Mar 11 🍅 Harvest: May 20 – Jul 8

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 Jefferson Parish

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

Soil pH

Your soil pH (5.0–6.1) is more acidic than Watermelon prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in Jefferson Parish warms quickly in spring but drains fast. Watermelon will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Watermelon.

Organic Matter

Organic matter is low (1.7%). Add 2-3 inches of compost before planting Watermelon.

How to Plant Watermelon

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Watermelon

5
successive plantings in your 325-day season

Sow every 8 weeks. Last sowing by Sep 09 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 1,180 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Watermelon

Watermelon needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Watermelon Needs Rainfall You Supplement Action
Jan 6.5" 4.6" 1.9" 💧 Light watering
Feb 6.5" 4.4" 2.1" 💧 Light watering
Mar 6.5" 4.8" 1.7" 💧 Light watering
Apr 6.5" 4.4" 2.1" 💧 Light watering
May 6.5" 4.1" 2.4" 💧 Light watering
Jun 6.5" 5.7" 0.8" 💧 Light watering
Jul 6.5" 5.9" 0.6" 💧 Light watering
Aug 6.5" 5.2" 1.3" 💧 Light watering
Sep 6.5" 3.6" 2.9" 💧 Light watering
Oct 6.5" 3.7" 2.8" 💧 Light watering
Nov 6.5" 4.8" 1.7" 💧 Light watering
Dec 6.5" 3.9" 2.6" 💧 Light watering

Water needs are for active growing months only (Jan–Dec in Jefferson Parish). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Watermelon 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.

Watermelon needs ~2,125 GDD — county provides 8,150 GDD Excellent fit

Watermelon Planting Timeline — Jefferson Parish, LA

Watermelon Planting Calendar

Activity When Date Range
Start Indoors December 30 Dec 30 – Jan 13
Transplant Outdoors February 3 Feb 3 – Feb 17
Direct Sow January 27 Jan 27 – Feb 17
Harvest April 14 Apr 14 – Jun 2

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 1-2 times/week

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9b

📆 Growing Season

325 days in Jefferson Parish

Growing Tips for Watermelon in Jefferson Parish

Direct sow Watermelon outdoors after January 27 in Jefferson Parish when soil has warmed and frost danger has passed.

Sandy soil in Jefferson Parish dries quickly — mulch Watermelon with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 100°F in Jefferson Parish, provide afternoon shade for Watermelon and water deeply in the morning.

Common pests for Watermelon in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 3-4 weeks early or direct sow after soil is warm. Plant on mounds with plenty of space. Check ripeness by looking for a yellow ground spot and dull thump when tapped.

Recommended Watermelon Varieties for Jefferson Parish

Full-size melons that thrive with your long season

Crimson Sweet (85d) Charleston Gray (85d) Moon and Stars (95d)

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Watermelon in Jefferson Parish, LA?

Jefferson Parish is in Zone 9b with an average last frost of January 27. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jefferson Parish, LA?

Jefferson Parish, Louisiana is in USDA Hardiness Zone 9b. The average last spring frost is January 27 and first fall frost is December 18.

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Your Jefferson Parish Garden Planner — Free

A 24-page printable planner built for Jefferson Parish (Zone 9b). 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 Jefferson Parish, LA. Local conditions may vary. Last updated: May 2026.

Sources & credits

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