Plant Sunflowers in Zone 4b
Seed-starting, transplant & harvest dates for USDA Zone 4b
Direct sow
May 12
Harvest (~80d)
Jul 31
In Zone 4b, 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 5
First fall frost
Sep 28
Growing season
146 days
Full Sunflowers grow guide → · All crops for Zone 4b →
Frequently asked questions
When should I start sunflowers in Zone 4b?
Direct sow outdoors around May 12.
Can I direct sow sunflowers in Zone 4b?
Yes, direct sow around May 12.