When to Plant Watermelon in Pennsylvania: Best Months and Last Planting Date
Plant watermelon in Pennsylvania from mid May in the southeast to early June in the mountains. See region dates, variety picks, and the too-late cutoff.
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When to Plant Watermelon in Pennsylvania
Plant watermelon in Pennsylvania after the last frost and once soil has warmed to at least 65 degrees F. For most of the state that means mid May to early June. The southeast corner around Philadelphia warms weeks ahead of the Allegheny mountains and the northern tier.
Southeast Pennsylvania and the lower Susquehanna Valley can usually plant in mid May. Pittsburgh and western Pennsylvania fit mid to late May. The mountains and the northern tier often need late May into early June, and frost pockets (low spots where cold air settles) in valleys can lag even longer. Use the watermelon by zone guide with your local frost date.
Pennsylvania Timing Notes
- Start seeds indoors 3 to 4 weeks before your outdoor date — transplants (young starter plants) buy back time in a short season.
- Harden off transplants — set them outside a little longer each day for about a week — before planting.
- Use black plastic or row cover (a light garden fabric that holds in warmth) to warm soil in cool springs.
- Choose a 70 to 80 day variety in the mountains and northern tier; the southeast has season enough for standard types.
Is It Too Late to Plant Watermelon in Pennsylvania?
In southeast Pennsylvania, a 70 day short-season variety planted by the end of June can still ripen before the typical mid to late October frost. In western Pennsylvania, treat mid to late June as the cutoff, and in the mountains and northern tier, mid June. Past your date, a large nursery transplant plus row cover in fall is the only late option worth trying.
Next Steps
Look up your county last frost date, confirm soil temperature, and favor a warm transplant over rushed seed. In Pennsylvania, the southeast can grow big melons — everyone else should reach for a short-season variety.