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When to Plant Watermelon in Gwinnett County, GA

Gwinnett County, Georgia Zone 8a May

This month in Gwinnett County, Georgia

A quick May briefing for Gwinnett County, Georgia gardeners — what's urgent, what's next, and what can wait.

Avg. last frost March 22
Avg. first frost November 13
Soil temp (4") 68°F
Watering Low
Pest pressure Moderate
Daylight 13.8 hrs
June prep starts now
  • 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.

Gwinnett County, Georgia is in USDA Zone 8a. The average last spring frost is March 22 and the first fall frost is November 13, giving you a growing season of approximately 236 days.

At an elevation of 127 feet, Gwinnett County receives approximately 55.9 inches of rainfall annually with predominantly clay loam soil. Summer highs average 88°F, providing good warmth for Watermelon during the growing season. Clay soil retains moisture well for Watermelon, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Watermelon root diseases.

Gwinnett County, GA (Zone 8a) Long season
236 days
Last Spring Frost March 22
236 growing days
First Fall Frost November 13
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Gwinnett County Soil Profile

Soil Type

Clay Loam

Soil pH

5.6-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (104 days to spare)
Start indoors: Feb 11 Transplant: Mar 25 🍅 Harvest: Jun 3 – Jul 22
Recommended (50%) ✓ Fits season (103 days to spare)
Start indoors: Feb 22 Transplant: Apr 5 🍅 Harvest: Jun 14 – Aug 2
Safe Start (90%) ✓ Fits season (102 days to spare)
Start indoors: Mar 12 Transplant: Apr 23 🍅 Harvest: Jul 2 – Aug 20

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 Gwinnett County

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

Soil pH

Your soil pH (5.6–6.6) overlaps with Watermelon's range (6.0–7.5), though not a perfect match.

Soil Texture

The clay loam soil in Gwinnett County is excellent for Watermelon — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Watermelon.

How to Plant Watermelon

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

Succession Planting Watermelon

3
successive plantings in your 236-day season

Sow every 8 weeks. Last sowing by Aug 05 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 1,061 gal / 100 sq ft

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 4.7" 0" ❄️ Dormant
Feb 4.6" 0" ❄️ Dormant
Mar 6.5" 5.7" 0.8" 💧 Light watering
Apr 6.5" 4.2" 2.3" 💧 Light watering
May 6.5" 4.2" 2.3" 💧 Light watering
Jun 6.5" 4.7" 1.8" 💧 Light watering
Jul 6.5" 6" 0.5" 💧 Light watering
Aug 6.5" 5.8" 0.7" 💧 Light watering
Sep 6.5" 3.7" 2.8" 💧 Light watering
Oct 6.5" 3.8" 2.7" 💧 Light watering
Nov 6.5" 4.5" 2" 💧 Light watering
Dec 3.9" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Gwinnett County). 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 ~1,360 GDD — county provides 3,776 GDD Excellent fit

Watermelon Planting Timeline — Gwinnett County, GA

Watermelon Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 – Mar 8
Transplant Outdoors April 5 Apr 5 – Apr 19
Direct Sow March 29 Mar 29 – Apr 19
Harvest June 14 Jun 14 – Aug 2

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 8a

📆 Growing Season

236 days in Gwinnett County

Growing Tips for Watermelon in Gwinnett County

Direct sow Watermelon outdoors after March 22 in Gwinnett County when soil has warmed and frost danger has passed.

With Gwinnett County's clay soil (32% clay), work in 3-4 inches of compost before planting Watermelon. Avoid tilling when soil is wet to prevent compaction.

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 Gwinnett County

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 Gwinnett County, GA?

Gwinnett County is in Zone 8a with an average last frost of March 22. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gwinnett County, GA?

Gwinnett County, Georgia is in USDA Hardiness Zone 8a. The average last spring frost is March 22 and first fall frost is November 13.

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Your Gwinnett County Garden Planner — Free

A 24-page printable planner built for Gwinnett County (Zone 8a). 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 Gwinnett County, GA. 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.