When to Plant Sunflower in Delaware
Sunflower (Helianthus annuus) is a fast-growing North American native annual famous for its towering stems and brilliant yellow heads. It thrives in full sun and heat, producing large, pollen-rich blooms that attract bees, butterflies, and seed-eating birds. Varieties range from 18-inch dwarfs to 12-foot giants and nearly every color except blue.
Delaware spans USDA hardiness zones 7b (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.
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Sunflower Planting Calendar for Delaware
▸ Zone 7b ~235 day growing season · Full guide →
Last frost: March 18 · First frost: November 8 · 235 day season
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 25 | Feb 25 – Mar 11 |
| Transplant Outdoors | March 18 | Mar 18 – Apr 1 |
| Direct Sow | March 18 | Mar 18 – Apr 8 |
| Bloom | June 10 | Jun 10 – Sep 30 |
Growing Tips for Delaware
Direct-sow 1 inch deep after last frost; germination takes 7-14 days at 65-75°F soil. Sunflowers dislike root disturbance so direct sowing is strongly preferred over transplanting. Plant in succession every 2 weeks for extended bloom. Stake tall varieties. Avoid overwatering — they tolerate drought once established. Birds will self-deadhead seed heads; leave them up through fall for wildlife.
Sunflower in Other States
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Sunflower in Delaware?
Planting dates for Sunflower in Delaware depend on your USDA zone. Delaware spans zones 7b. Check the planting calendar above for your specific zone's frost dates and planting windows.
What zone is Delaware for planting?
Delaware contains USDA hardiness zones 7b. Your specific zone depends on your location within the state — northern and higher-elevation areas are in colder zones, while southern and coastal areas are warmer.