Onions (bulbing) planting calendar for USDA Zone 6a

Western NC mountains, southern PA, central OH, northern MO. Average last spring frost May 1, first fall frost October 1 — a 153-day frost-free season.

Zone fit: challenging
Short-day onion varieties bulb best in Zones 7 and warmer; northern growers should choose intermediate-day types instead.

Key dates

Start seeds indoors
February 13 – February 27
Transplant outdoors
March 13 – April 3
Expected first harvest
June 28 – July 26

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 6a

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 6a

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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