Storage Onions

All the varieties we list are suitable for northern growers. If you live farther south, note our latitude specifications at the end of each description.

• Long-day: Must be north of 36° latitude, though some long-day types perform best north of 40°. These onions need 14-16 hours of sun a day to trigger bulb formation. May not perform well in continually hot soil temps.
• Intermediate-day: Also called day-neutral onions, generally need 12-15 hours of daylight to bulb. Some can do well in parts of the upper southern U.S. all the way up through Maine. Others are best for mid-latitudes only (35-40°). All intermediate-day onions in our catalog have performed well repeatedly in our Maine trials.
• Short-day: Suited for the South, below latitude 36°, bulbing when the day length measures between 10–12 hours. We don’t offer seed for short-day varieties.)

About 200-250 seeds/g, 5,700-7,000 seeds/oz.

Growing Onions

Shallow rooted, onion require rich weed-free soil and consistent water. All other factors being equal, onions grown from seedlings will grow bigger and resist disease better than set-grown onions.

• Planting: Plant seedlings and sets in spring as soon as soil is workable (onion plants come with planting directions). Onions survive light frosts.
  • Seedlings: Set seedlings out in shallow trenches 1–2" deep. Plant 6–8" apart, with 1–2' between rows.
  • Sets: Plant onion sets 3" apart in rows 1' apart. Thin to 6" apart as they grow (or plant them 4–6" apart if you don’t want to thin).
• Growing: Mulch when they are 1' tall. During the season, pull any plants that begin to bolt and use them as scallions. It’s a good idea to sidedress once or twice a season, especially close to summer solstice.
• Harvest: After half the onion tops fall, push over the remainder and harvest within a week.
• Curing: Field-cure in the sun about 10 days until dry, covering with a tarp in wet weather. In the event of extreme heat or prolonged damp conditions, we recommend sheltered curing in a well-ventilated barn or greenhouse. Curing is essential for long storage.
• Storage: Store cured onions in mesh sacks in a cool dry well-ventilated place, periodically removing sprouting or rotting bulbs. Ideal storage conditions are temperatures at 32° with humidity of 60–70%. If you can’t do that, work to get a total number of 100. For example, at temperatures from 50–55°, humidity should be 45–50%. In spring, put your remaining onions in the fridge to extend storage until your new crop is ready.

Note: Onion seed is short-lived. Retest 1-year-old seed before using. Discard anything older.