The Best Time to Plant Onion Sets in the Northeast

Spring

• Onions are cool-weather crops that are normally planted in late winter and early spring. Onions are grown from plants, seeds or from small bulbs, which are called sets. Sets should be 3/4 inch in diameter. Large bulbs tend to bolt, meaning they rapidly mature and begin seeding without growing an edible root. Plant sets up to a month before your region's last frost date. In the Northeast the last frost date is usually in mid-April but this date can vary from region to region. Areas on the coast may have an earlier spring than inland, mountainous areas. Local weather forecasters usually inform their viewers of the last frost date but you may also consult almanacs and local gardening clubs for more information.

Summer

• Grow your own onion sets in the middle of the summer growing season. Sow seeds thickly within a small area and allow the seeds to germinate. Within eight weeks the tops should emerge. Pull down the tops and force the bulbs. Remove the plants when their bulbs are about the size of dime. Cut back the tops to within 1/4 inch of the bulb. Dry the bulbs. The sets will be ready to plant in the spring.

Fall and Winter

• Onions are biennial crops that are used as annuals. Once the plant has flowered it dies, regardless of whether or not it has been harvested. Onions do not not stay dormant through fall and winter freezes and do not replenish themselves by spring. Planting new onions in fall and winter results in crop failure. Though the onions are capable of surviving frost, the cold that they endured through these months will cause them to "bolt," meaning they flower early and go to seed.

Considerations

• Purchase onion sets early in the season. The longer the bulbs stay under store lights, the more likely they will dry out and fail to produce a good crop. Short-day onions are the preferred variety in the Northeast. Short-day onions are acclimated to mature and produce even when sunlight is limited. Southern, long day varieties like Vidalia do not produce in the Northeast's short growing season.