Plant Sunflowers in Zone 4a
Seed-starting, transplant & harvest dates for USDA Zone 4a
Direct sow
May 17
Harvest (~80d)
Aug 5
In Zone 4a, the average last spring frost is around May. Sunflowers is a half-hardy crop, so sow it directly around the dates above.
Last spring frost
May 10
First fall frost
Sep 22
Growing season
135 days
Full Sunflowers grow guide → · All crops for Zone 4a →
Frequently asked questions
When should I start sunflowers in Zone 4a?
Direct sow outdoors around May 17.
Can I direct sow sunflowers in Zone 4a?
Yes, direct sow around May 17.