Onions (bulbing) planting calendar for USDA Zone 9b

Orlando, Tampa, San Antonio, southern LA coast. Average last spring frost February 5, first fall frost December 15 — a 313-day frost-free season.

Zone fit: good
Cool-season crops bolt fast under Zone 9b heat. Prioritize the fall planting window and use shade cloth for any spring succession.

Key dates

Start seeds indoors
November 20 – December 4
Transplant outdoors
December 18 – January 8
Expected first harvest
April 4 – May 2

Windows are calculated from your zone's average frost dates. Adjust ±1 week for microclimates, elevation, and your own frost records.

Spacing and soil

Plant spacing
4″
Row spacing
12″
Seed depth
0.25″
Soil temperature
50–75°F
Frost tolerance
hardy
Days to harvest
100 days

Grower notes for Zone 9b

Southeast growers must plant short-day varieties. Long-day types will make tops but never bulb below 36° latitude.

Plant near: carrots, beets, lettuce

Keep away from: beans, peas

Other alliums for Zone 9b

Same crop, other zones

Track your own plantings

BAU Farm Intelligence turns these windows into per-field tasks — indoor seed-start reminders, transplant dates, harvest projections — using your farm's actual frost history.

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