When to plant onions (bulbing) in USDA Zone 9a

Plan your onions (bulbing) planting around local frost risk and soil temperature, then work backward from the harvest week your buyers need. The calendar below is a starting point, not a field-level weather forecast.

Gainesville FL, Houston, New Orleans, southern GA coast. Average last spring frost February 25, first fall frost December 1 — a 279-day frost-free season.

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

Key dates

Start seeds indoors
December 10 – December 24
Transplant outdoors
January 7 – January 28
Expected first harvest
April 24 – May 22

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 9a

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 9a

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.