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Published on 10/20/97

Start Now to Grow Your Own Sweet Onions

You may not have finished the Vidalia onions from last season, but commercial growers are starting now on their onion crop for next year.

If you're an avid gardener and pine for something to grow in the winter, maybe sweet onions are for you.

The sandy soils in the southern half of Georgia are ideal for growing sweet onions. This is because these soils tend to be low in sulfur, a major contributor to making onions hot.

To start with, get the right kind of seed. The onions we grow in the South are called short-day onions. They bulb (form an onion) during the short days of winter. Other types called intermediate and long- day onions won't form a bulb as readily during short winter days.

The seeds are very small and should be planted about one- fourth of an inch deep. You can plant them from the beginning of September to the end of October.

Because they're so small, take care with watering so the top one-fourth inch of soil always remains moist. Your seedlings should be visible in 10-14 days.

Onions should have a final spacing of about 4-5 inches in the row so there is plenty of room for the bulb to form. Commercial growers typically seed plant beds with 60-70 seeds per foot of row. They grow these onions for eight weeks, then pull them to transplant to the final spacing of about 4-5 inches.

If you don't want to go to the trouble of growing onions from seed, transplants are usually available in late winter and early spring from your garden supply or department store. Local growers may share some of their extra transplants, too.

Onions are usually transplanted from plant beds to their final spacing between Thanksgiving and Christmas. But they can be transplanted as late as the end of February.

To produce a mild onion, select the right variety (short-day sweet onion type), keep it watered throughout the growing season and go easy on the fertilizer. Go especially light on sulfur-containing products. These increase the onions' pungency.

Onions should be ready for harvest from April into June, depending on variety and weather. You'll know when it's time to harvest when 20 percent of the onion tops have fallen over at the neck.

George Boyhan is a Cooperative Extension horticulturist with the University of Georgia College of Agricultural and Environmental Sciences