When to Plant Watermelon in Duval County, TX
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.
Duval County, Texas is in USDA Zone 9a. The average last spring frost is February 13 and the first fall frost is December 9, giving you a growing season of approximately 299 days.
At an elevation of 4,259 feet, Duval County receives approximately 55.2 inches of rainfall annually with predominantly loam soil. Summer highs average 102°F, so Watermelon may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Watermelon root diseases.
Duval County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.3
Drainage
Well Drained
Plant Planting Risk Windows
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 Duval County
How your county's soil matches Watermelon's growing requirements.
Soil pH
Your soil pH (6.8–7.3) is within Watermelon's preferred range (6.0–7.5).
Soil Texture
The loam soil in Duval County is excellent for Watermelon — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.1%). Annual compost additions will help Watermelon.
How to Plant Watermelon
Succession Planting Watermelon
Sow every 8 weeks. Last sowing by Aug 31 to harvest before frost.
Plant Water Budget
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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | 6.5" | 1.7" | 4.8" | 🚿 Regular watering |
| Mar | 6.5" | 4" | 2.5" | 💧 Light watering |
| Apr | 6.5" | 5.3" | 1.2" | 💧 Light watering |
| May | 6.5" | 8.7" | 0" | ✅ Rainfall sufficient |
| Jun | 6.5" | 8.4" | 0" | ✅ Rainfall sufficient |
| Jul | 6.5" | 6.8" | 0" | ✅ Rainfall sufficient |
| Aug | 6.5" | 6" | 0.5" | 💧 Light watering |
| Sep | 6.5" | 5.7" | 0.8" | 💧 Light watering |
| Oct | 6.5" | 3.6" | 2.9" | 💧 Light watering |
| Nov | 6.5" | 1.9" | 4.6" | 🚿 Regular watering |
| Dec | 6.5" | 1.6" | 4.9" | 🚿 Regular watering |
Water needs are for active growing months only (Feb–Dec in Duval 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 Planting Timeline — Duval County, TX
Watermelon Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 16 | Jan 16 – Jan 30 |
| Transplant Outdoors | February 20 | Feb 20 – Mar 6 |
| Direct Sow | February 13 | Feb 13 – Mar 6 |
| Harvest | May 1 | May 1 – Jun 19 |
Plant 1" deep · 30" apart · Rows 42" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Transplant Outdoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 9a
📆 Growing Season
299 days in Duval County
Growing Tips for Watermelon in Duval County
Direct sow Watermelon outdoors after February 13 in Duval County when soil has warmed and frost danger has passed.
With summer highs reaching 102°F in Duval County, 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 Duval County
Full-size melons that thrive with your long season
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Watermelon in Other Locations
Frequently Asked Questions
When should I plant Watermelon in Duval County, TX?
Duval County is in Zone 9a with an average last frost of February 13. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.
What planting zone is Duval County, TX?
Duval County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 13 and first fall frost is December 9.
Plan Your Garden with Confidence
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