When to Plant Watermelon in Iowa: Best Months and Last Planting Date
Plant watermelon in Iowa from mid May in the south to early June up north, once soil hits 65°F. See region dates, variety picks, and the too-late cutoff.
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When to Plant Watermelon in Iowa
Plant watermelon in Iowa after the last frost and once soil has warmed to at least 65 degrees F. For most Iowa gardens, that means mid May to early June. Southern Iowa warms a week or two ahead of northern Iowa, so use your county frost date rather than a single statewide date.
Southern Iowa can often plant in mid May. Central Iowa usually fits mid to late May. Northern Iowa may need late May into early June, especially after a cold, wet spring. Use the watermelon by zone guide with your local last frost date before planting.
Iowa Timing Notes
- Start seeds indoors 3 to 4 weeks before your outdoor date — Iowa's season is short enough that transplants pay off.
- 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 a slow spring.
- Choose a 70 to 80 day short-season or icebox variety (a small, refrigerator-sized melon); Iowa's first frost often arrives in early to mid October.
Is It Too Late to Plant Watermelon in Iowa?
In southern Iowa, a 70 day short-season variety planted by late June can still ripen before the typical early to mid October frost. In central and northern Iowa, treat mid to late June as the practical cutoff. After that, a large nursery transplant is the only late option worth trying, and even then protect vines from early fall frost with row cover.
When Is Watermelon Season in Iowa?
Watermelon season in Iowa runs from early August through late September. Gardens planted in mid to late May start ripening in the first half of August, and farm stands peak in mid to late August. By early October, frost usually ends the season. If you are buying local, August is the sweet spot; if you are growing, count about 80 days forward from your planting date.
Next Steps
Look up your county last frost date, confirm soil is at least 65 degrees F, and favor a warm transplant over seed rushed into cold ground. In Iowa, short-season varieties and warm starts make the difference.