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When to Plant Watermelon in Runnels County, TX

Watermelon
Runnels County, Texas Zone 8a July

Your July gardening checklist

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

Avg. last frost March 19
Avg. first frost November 15
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 13.9 hrs
  1. Harvest watermelon as they ripen

    If you can't use it all right away, check the food-preservation section of your planner.

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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.

Runnels County, Texas is in USDA Zone 8a. The average last spring frost is March 19 and the first fall frost is November 15, giving you a growing season of approximately 241 days.

At an elevation of 4,833 feet, Runnels County receives approximately 47.6 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Watermelon during the growing season.

Runnels County, TX (Zone 8a) Long season
241 days
Last Spring Frost March 19
241 growing days
First Fall Frost November 15

Runnels County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.1

Drainage

Well Drained

Watermelon Planting Risk Windows

Early Start (70% safe) ✓ Fits season (112 days to spare)
Start indoors: Feb 9 Transplant: Mar 23 🍅 Harvest: Jun 1 – Jul 20
Recommended (50%) ✓ Fits season (108 days to spare)
Start indoors: Feb 19 Transplant: Apr 2 🍅 Harvest: Jun 11 – Jul 30
Safe Start (90%) ✓ Fits season (100 days to spare)
Start indoors: Mar 15 Transplant: Apr 26 🍅 Harvest: Jul 5 – Aug 23

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 Runnels County

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

Soil pH

Your soil pH (6.3–7.1) is within Watermelon's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is low (2.0%). 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

4
successive plantings in your 241-day season

Sow every 8 weeks. Last sowing by Aug 07 to harvest before frost.

Watermelon Water Budget

Plant needs
1.5″/week
Rainfall provides
0.8″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,438 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 1" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 6.5" 3" 3.5" 🚿 Regular watering
Apr 6.5" 4.9" 1.6" 💧 Light watering
May 6.5" 7.4" 0" ✅ Rainfall sufficient
Jun 6.5" 8.1" 0" ✅ Rainfall sufficient
Jul 6.5" 6.3" 0.2" 💧 Light watering
Aug 6.5" 5.1" 1.4" 💧 Light watering
Sep 6.5" 4.2" 2.3" 💧 Light watering
Oct 6.5" 3.2" 3.3" 🚿 Regular watering
Nov 6.5" 1.5" 5" 🚿 Regular watering
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Runnels 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 ~1,488 GDD — county provides 4,217 GDD Excellent fit

Watermelon Planting Timeline — Runnels County, TX

Watermelon Planting Calendar

Activity When Date Range
Start Indoors February 19 Feb 19 – Mar 5
Transplant Outdoors April 2 Apr 2 – Apr 16
Direct Sow March 26 Mar 26 – Apr 16
Harvest June 11 Jun 11 – Jul 30

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
September
October
November
December

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: ideal

🗺️ USDA Zone

Zone 8a

📆 Growing Season

241 days in Runnels County

Growing Tips for Watermelon in Runnels County

Direct sow Watermelon outdoors after March 19 in Runnels County when soil has warmed and frost danger has passed.

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 Runnels 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 Runnels County, TX?

Runnels County is in Zone 8a with an average last frost of March 19. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Runnels County, TX?

Runnels County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 19 and first fall frost is November 15.

🌱

Your Runnels County Garden Planner — Free

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

Sources & credits

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