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When to Plant Watermelon in Passaic County, NJ

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.

Passaic County, New Jersey is in USDA Zone 6b. The average last spring frost is March 29 and the first fall frost is November 12, giving you a growing season of approximately 228 days.

At an elevation of 932 feet, Passaic County receives approximately 48.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Watermelon during the growing season.

Passaic County, NJ (Zone 6b) Long season
228 days
Last Spring Frost March 29
228 growing days
First Fall Frost November 12

Passaic County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (95 days to spare)
Start indoors: Feb 18 Transplant: Apr 8 🍅 Harvest: Jun 17 – Aug 5
Recommended (50%) ✓ Fits season (95 days to spare)
Start indoors: Feb 22 Transplant: Apr 12 🍅 Harvest: Jun 21 – Aug 9
Safe Start (90%) ✓ Fits season (104 days to spare)
Start indoors: Mar 5 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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 220 gal / 100 sq ft
Watermelon needs ~1,296 GDD — county provides 3,477 GDD Excellent fit

Watermelon Planting Timeline โ€” Passaic County, NJ

Watermelon Planting Calendar

Activity When Date Range
Start Indoors February 22 Feb 22 โ€“ Mar 8
Transplant Outdoors April 12 Apr 12 โ€“ Apr 26
Direct Sow April 5 Apr 5 โ€“ Apr 26
Harvest June 21 Jun 21 โ€“ Aug 9

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

Month-by-Month Timeline

MonthActivities
January โ€”
February Start Indoors
March Start Indoors
April Transplant Outdoors Direct Sow
May โ€”
June Harvest
July Harvest
August Harvest
September โ€”
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 6b

Growing Season

228 days

Growing Tips for Passaic 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 Passaic County, NJ?

Passaic County is in Zone 6b with an average last frost of March 29. Plan your Watermelon planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Passaic County, NJ?

Passaic County, New Jersey is in USDA Hardiness Zone 6b. The average last spring frost is March 29 and first fall frost is November 12.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Passaic County gardeners in Zone 6b 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 Passaic County, NJ. Local conditions may vary. Last updated: April 2026.