Plant Sunflowers in Zone 3b
Seed-starting, transplant & harvest dates for USDA Zone 3b
Direct sow
May 20
Harvest (~80d)
Aug 8
In Zone 3b, 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 13
First fall frost
Sep 18
Growing season
128 days
Full Sunflowers grow guide → · All crops for Zone 3b →
Frequently asked questions
When should I start sunflowers in Zone 3b?
Direct sow outdoors around May 20.
Can I direct sow sunflowers in Zone 3b?
Yes, direct sow around May 20.