Annual Flower

When to Plant Sunflowers in Delaware

Few things bring more joy than a row of sunflowers turning their faces to the sun. Easy, dramatic, and pollinator-friendly.

The Short Answer

In Delaware, plant sunflowers based on your regional frost dates. Northern Delaware has a last frost around Apr 10 - Apr 25, while Southern Delaware sees frost end around Apr 1 - Apr 15. Moderate climate with maritime influence. Good growing conditions for a wide range of vegetables.

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

Sunflowers 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
2 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Southern Delaware (Zones 7b)

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

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

Growing Sunflowers in Delaware

Sunflowers in Delaware's Climate

Sunflowers are nearly foolproof in moderate climates. Direct sow after frost and watch them grow a foot or more per week in the summer heat. Succession plant every 2 weeks through late June for blooms all summer. Your reliable warm season gives even the tallest mammoth varieties plenty of time to mature.

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 55°F before planting sunflowers outside.

Delaware Climate & Growing Season

Moderate climate with maritime influence. Good growing conditions for a wide range of vegetables. Sunflowers 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 sunflowers — transplant timing shifts by several weeks across the state.

Growing Tips

Direct sow is preferred — sunflowers don't love transplanting. Succession plant every 2 weeks for blooms all summer.

Companion Planting

Plant sunflowers alongside these companions for better growth:

Cucumbers Squash Corn

Keep sunflowers away from:

Potatoes

The Bottom Line

Sunflowers 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.

Related Guides

Sunflowers Growing Guide National planting guide with all states Delaware Planting Calendar All plants for Delaware Sunflowers in Alabama Alabama planting dates Sunflowers in Alaska Alaska planting dates Sunflowers in Arizona Arizona planting dates Sunflowers 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

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