Plant Onions in Zone 9b
Seed-starting, transplant & harvest dates for USDA Zone 9b
Start indoors
Dec 7
Transplant
Feb 1
Harvest (~100d)
May 12
In Zone 9b, the average last spring frost is around February. Onions is a hardy crop, so give it a head start indoors about 10 weeks before that, then move it out after frost danger passes.
Last spring frost
Feb 15
First fall frost
Dec 10
Growing season
298 days
Full Onions grow guide → · All crops for Zone 9b →
Frequently asked questions
When should I start onions in Zone 9b?
Start onions seeds indoors around Dec 7 (Zone 9b).
Can I direct sow onions in Zone 9b?
Onions is best started indoors and transplanted in Zone 9b rather than direct sown.