- Short-day onions start developing bulbs when the day length reaches 10 to 12 hours. These are most suited to southern parts of the U.S. — roughly the southern half of California to the tip of South Carolina — where onions can be planted in fall or winter and enjoy a long growing season.
- Long-day onions don't begin forming bulbs until the day length is 14 to 16 hours per day. These are best for the northern states — from northern Maryland to Oregon and north into Canada. Northern gardeners can grow short-day onions, too, but they won't get as large as those grown in the South.
- Intermediate-day onions start forming bulbs when day length is 12 to 14 hours per day and can be grown anywhere except the most southern parts of Texas and Florida.
Do you plant seeds, seedlings or sets? Which have been the most successful for you? Let us know, with pictures if you have them.
An easy way to plant green onions: A strip of biodegradable paper is embedded with perfectly spaced seeds; simply unroll into a planting furrow and cover. Planting is precise, there's little or no thinning needed.Onions can be grown from any of these life stages: seed, seedling or dormant bulb. Here's how to choose which ones to grow.
- Sets are small dormant bulbs that grew from seed the previous season. Sets are commonly available and sold by the pound in spring at garden centers. Plant about 1-1/2 to 2-1/2" deep. They are best for growing scallions, which are harvested before the plants "bolt" or produce flower stalks. They can produce bulbs, but they won't be as large as those grown from seeds or seedlings.
- Seeds are the way to grow the widest variety of onions, including many uncommon and heirloom varieties. In most of the country, they must be started indoors and grown under lights at least two months before you plan to set them into the garden, or about 10 to 14 weeks before your last frost date. Because they are first-year plants, they will make large bulbs.
- Seedlings are plants that were started from seed in the current season. You can purchase them in bundles from mail-order nurseries, or in multi-packs from garden centers. Because they are first-year plants, you can expect large bulbs.
Harvest them as needed. Store in the refrigerator for up to a week.
- Sweet onion varieties generally contain at least 6 percent sugar, lots of water and very little sulfur. Nearly all short-day or southern onions are of the sweet variety. Sweet onions, such as the Vidalia or Walla-Walla, are less sweet when grown in New England, where the soil contains more sulfur than it does in the South or far West. These mild-flavored onions can be eaten raw and are best used within a few weeks of harvest.
- Storage onions usually contain less than 5 percent sugar and have higher levels of sulfur, which gives them a long storage life and greater pungency. Curing the bulbs after harvest further reduces their water content and increases their storage life. Storage onions have more intense flavor and are used primarily for cooking.
We sold out of onions (some I kept) early at the Farmers Market so this year we will be planting three times and many. It was really exciting pulling those giant onions out of the garden. Many people down at the market wanted to know if we grew these. A sure indication that they looked and tasted good.