Annual Flower

When to Plant Sunflowers in Pennsylvania

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

The Short Answer

Sunflowers are a Pennsylvania summer classic — easy, dramatic, and rewarding from the first planting. The crop grows well in every corner of the state and provides food for birds and pollinators while brightening the garden.

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

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

Growing Sunflowers in Pennsylvania

State-Specific Growing Tips

Direct sow from mid-May. Succession plant every 2 weeks through late June. Pennsylvania's varied soils all support sunflowers. Full sun, moderate water. Stake tall varieties.

Recommended Varieties for Pennsylvania

Mammoth, ProCut, Autumn Beauty. Penn State Extension recommends sunflowers for wildlife gardens.

Common Challenges in Pennsylvania

Birds and squirrels eat seeds. Deer browse young plants. Powdery mildew in humid late summer.

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 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

Sunflowers Growing Guide National planting guide with all states Pennsylvania Planting Calendar All plants for Pennsylvania 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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