Warm-Season Vegetable

When to Plant Watermelon in Pennsylvania

The ultimate summer treat. Watermelons need heat, space, and patience — but the payoff is pure joy.

The Short Answer

Watermelon growing in Pennsylvania pushes the northern edge of reliable melon country. Southeast Pennsylvania's Zone 7a conditions provide enough heat and season length for success with short-season varieties and transplants. The rest of the state needs more aggressive season extension. Pennsylvania watermelons will never match Florida or Texas for size, but a sun-warmed Sugar Baby from your own garden is incomparably satisfying.

Pennsylvania Frost Dates

Your planting dates depend on which part of Pennsylvania you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Northern Pennsylvania 5a, 5b, 6a May 5 - May 20 Sep 20 - Oct 5
Central Pennsylvania 5b, 6a, 6b Apr 25 - May 10 Oct 1 - Oct 15
Philadelphia Region 7a, 7b Apr 5 - Apr 20 Oct 15 - Nov 5

Watermelon Planting Schedule for Pennsylvania

Northern Pennsylvania (Zones 5a, 5b, 6a)

Average last frost: May 5 - May 20 · Average first frost: Sep 20 - Oct 5

Start Seeds Indoors
3 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
3 wks after frost

Central Pennsylvania (Zones 5b, 6a, 6b)

Average last frost: Apr 25 - May 10 · Average first frost: Oct 1 - Oct 15

Start Seeds Indoors
3 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
3 wks after frost

Philadelphia Region (Zones 7a, 7b)

Average last frost: Apr 5 - Apr 20 · Average first frost: Oct 15 - Nov 5

Start Seeds Indoors
3 wks before frost
Transplant Outside
2 wks after frost
Direct Sow
3 wks after frost

Growing Watermelon in Pennsylvania

State-Specific Growing Tips

Start seeds indoors 3 weeks before last frost. Transplant in late May (southeast PA) to early June (central PA) when soil reaches 70°F. Northern PA is marginal for watermelons. Black plastic mulch is essential everywhere. Row cover during cool nights in June adds critical warmth. Choose the warmest, most sun-exposed garden spot available. Raised mounds with compost improve drainage in Pennsylvania's clay-loam soils.

Recommended Varieties for Pennsylvania

Short-season varieties only. Sugar Baby (75 days) is the most reliable. Blacktail Mountain (75 days) was bred for northern conditions. New Hampshire Midget (68 days) for the shortest guarantee. Southeast PA gardeners with warm microclimates can try Crimson Sweet (80 days). Penn State Extension recommends starting with icebox types before attempting full-size melons.

Common Challenges in Pennsylvania

Insufficient heat in most years outside southeastern PA. Cool nights delay ripening. Fusarium wilt in heavy soils. Cucumber beetles and bacterial wilt. Anthracnose during humid summers. Groundhogs gnaw on young vines.

Growing Tips

Black plastic mulch warms soil faster. Check ripeness by looking for a yellow ground spot and listening for a hollow thump.

Companion Planting

Plant watermelon alongside these companions for better growth:

Corn Sunflowers Marigolds

Keep watermelon away from:

Potatoes

The Bottom Line

Watermelon can be grown successfully in Pennsylvania with proper attention to regional frost dates and local growing conditions. Timing varies across the state — Northern Pennsylvania gardeners work with a last frost around May 5 - May 20, while Philadelphia Region sees frost end around Apr 5 - Apr 20. Choose varieties suited to your region, amend your soil based on its specific needs, and monitor for the pests and diseases most common in your area. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Watermelon Growing Guide National planting guide with all states Pennsylvania Planting Calendar All plants for Pennsylvania Watermelon in Alabama Alabama planting dates Watermelon in Alaska Alaska planting dates Watermelon in Arizona Arizona planting dates Watermelon in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

Ready to Start Planting?

Enter your zip code and pick your plant. We'll tell you exactly when to plant, start seeds, and harvest — based on where you live.

Find Your Planting Dates