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When to Plant Watermelon in Jasper 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.

Jasper County, Indiana is in USDA Zone 5b. The average last spring frost is April 24 and the first fall frost is October 17, giving you a growing season of approximately 176 days.

At an elevation of 1,082 feet, Jasper County receives approximately 36.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Watermelon to ensure they mature before fall.

Jasper County, IN (Zone 5b) Moderate season
176 days
Last Spring Frost April 24
176 growing days
First Fall Frost October 17

Jasper County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (42 days to spare)
Start indoors: Mar 15 Transplant: May 3 🍅 Harvest: Jul 12 – Aug 30
Recommended (50%) ✓ Fits season (43 days to spare)
Start indoors: Mar 20 Transplant: May 8 🍅 Harvest: Jul 17 – Sep 4
Safe Start (90%) ✓ Fits season (43 days to spare)
Start indoors: Apr 2 Transplant: May 21 🍅 Harvest: Jul 30 – Sep 17

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
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 664 gal / 100 sq ft
Watermelon needs ~1,041 GDD — county provides 2,156 GDD Excellent fit

Watermelon Planting Timeline โ€” Jasper County, IN

Watermelon Planting Calendar

Activity When Date Range
Start Indoors March 20 Mar 20 โ€“ Apr 3
Transplant Outdoors May 8 May 8 โ€“ May 22
Direct Sow May 1 May 1 โ€“ May 22
Harvest July 17 Jul 17 โ€“ Sep 4

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

176 days

Growing Tips for Jasper 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 Jasper County, IN?

Jasper County is in Zone 5b with an average last frost of April 24. Plan your Watermelon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Jasper County, IN?

Jasper County, Indiana is in USDA Hardiness Zone 5b. The average last spring frost is April 24 and first fall frost is October 17.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Jasper 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 Jasper County, IN. Local conditions may vary. Last updated: April 2026.