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When to Plant Watermelon in Randolph County, IN

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.

Randolph County, Indiana is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 16, giving you a growing season of approximately 173 days.

At an elevation of 602 feet, Randolph County receives approximately 40.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Watermelon to ensure they mature before fall.

Randolph County, IN (Zone 5b) Moderate season
173 days
Last Spring Frost April 26
173 growing days
First Fall Frost October 16

Randolph County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (36 days to spare)
Start indoors: Mar 18 Transplant: May 6 🍅 Harvest: Jul 15 – Sep 2
Recommended (50%) ✓ Fits season (40 days to spare)
Start indoors: Mar 22 Transplant: May 10 🍅 Harvest: Jul 19 – Sep 6
Safe Start (90%) ✓ Fits season (34 days to spare)
Start indoors: Apr 7 Transplant: May 26 🍅 Harvest: Aug 4 – Sep 22

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 31 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Watermelon needs ~1,105 GDD — county provides 2,249 GDD Excellent fit

Watermelon Planting Timeline โ€” Randolph County, IN

Watermelon Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 โ€“ Apr 5
Transplant Outdoors May 10 May 10 โ€“ May 24
Direct Sow May 3 May 3 โ€“ May 24
Harvest July 19 Jul 19 โ€“ Sep 6

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

70โ€“100 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5b

Growing Season

173 days

Growing Tips for Randolph County

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.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Level Up Your Garden

Frequently Asked Questions

When should I plant Watermelon in Randolph County, IN?

Randolph County is in Zone 5b with an average last frost of April 26. Plan your Watermelon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Randolph County, IN?

Randolph County, Indiana is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 16.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Randolph County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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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 Randolph County, IN. Local conditions may vary. Last updated: April 2026.