Warm-Season Vegetable

When to Plant Watermelon in Delaware

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

The Short Answer

In Delaware, watermelon planting dates vary by region. In Northern Delaware, your average last frost is around Apr 10 - Apr 25, while Southern Delaware sees its last frost around Apr 1 - Apr 15. Since watermelon are frost-sensitive, start seeds indoors 3 weeks before your last frost, then transplant outside 2 weeks after frost danger has passed. Sandy soils in south, clay loam in north. Generally well-drained. Slightly acidic.

Delaware Frost Dates

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

Region	Zones	Last Frost (Spring)	First Frost (Fall)
Northern Delaware	7a	Apr 10 - Apr 25	Oct 10 - Oct 25
Southern Delaware	7b	Apr 1 - Apr 15	Oct 20 - Nov 5

Watermelon Planting Schedule for Delaware

Northern Delaware (Zones 7a)

Average last frost: Apr 10 - Apr 25 · Average first frost: Oct 10 - Oct 25

Start Seeds Indoors

3 wks before frost

Transplant Outside

2 wks after frost

Direct Sow

3 wks after frost

Southern Delaware (Zones 7b)

Average last frost: Apr 1 - Apr 15 · Average first frost: Oct 20 - Nov 5

Start Seeds Indoors

3 wks before frost

Transplant Outside

2 wks after frost

Direct Sow

3 wks after frost

Growing Watermelon in Delaware

Watermelon in Delaware's Climate

Watermelon is achievable with transplants and short-to-medium season varieties. Start indoors 3 weeks before last frost. Black plastic mulch warms soil for earlier transplanting. Crimson Sweet (80 days) is the most popular variety. Your warm July-August provides the sustained heat watermelons need for sweetness.

Soil Considerations for Delaware

Sandy soils in south, clay loam in north. Generally well-drained. Slightly acidic. Make sure soil has warmed to at least 70°F before planting watermelon outside.

Delaware Climate & Growing Season

Moderate climate with maritime influence. Good growing conditions for a wide range of vegetables. Watermelon cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.

Growing season length varies across Delaware: Northern Delaware (7a) has a last frost around Apr 10 - Apr 25, while Southern Delaware (7b) sees frost end around Apr 1 - Apr 15. This difference matters for watermelon — transplant timing shifts by several weeks across the state.

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 across Delaware, but your exact planting dates depend on which region you're in. Northern Delaware gardeners should plan around a Apr 10 - Apr 25 last frost, while those in Southern Delaware can typically plant earlier. For exact dates based on your zip code, use our free planting date finder.

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