How to Grow Onions: Varieties for Every Region

Learn how to grow onions and discover which onion varieties are the best choices for your garden and kitchen.

| February/March 2006

Onions occupy an important place in the culinary world due to their wide variety and versatility. Sweet and mild onions can be enjoyed raw in salads or lightly cooked in summer salsas and stir-fries, while pungent varieties add body and flavor to meats, marinaras and winter soups. If bulb onions aren’t near the top of your shopping or garden-planting list, they should be. Many varieties of onions make excellent storage crops, so learn how to grow onions in your garden and reap a harvest of beautiful bulbs that will enliven your kitchen in any season.

Cooking and Cutting Onions

“There are no bad onions; you just have to use them correctly,” says Bill Randle, a professor of horticulture at the University of Georgia who specializes in onion flavor. The pungency of onions can be rated on a numeric scale based on the amount of pyruvic acid present in the bulbs. For example, ‘Yellow Granex’ — the type of onion often called a ‘Vidaliai’ — is among the mildest onions and might rate between 1 and 4, while many other sweet onion varieties — such as the ‘Texas Super Sweet’ — have ratings between 3 and 5. Storage onions, often called dry onions, contain more pyruvic acid and often rate between 7 and 12.

Many storage onions are delicious when cooked, but almost inedible when raw. “Most people can’t hold a raw 8 in their mouth,” Randle says. “But when I’m making chili, that’s what I want.” Cooking spicy storage onions not only adds flavor to food, but can make the onions quite sweet (see “Caramelized Onions” later in this article).

Onions are complex chemical powerhouses, but their fury is not unleashed until they are cut. As soon as the cells are opened, a cascade of eye-irritating sulfur compounds hits the air. Cooks have many methods for taking the tears out of chopping onions, but according to Randle, the best idea is to chill the onion first. “The irritating compounds volatize at 50 degrees, so if the onion temperature is lower than that, it won’t make you cry,” he says. The chef’s trick of leaving the base of the onion intact can help, too, because pungency compounds are most concentrated in the base and center of the bulb.

Want to turn up the volume of onion flavor? Finely chopping onions increases the number of open cells, which delivers more flavor to cooked foods than leaving onions in larger pieces.

When chopped onions are left to sit, their flavor compounds continue to change and rearrange themselves, which can lead to bitter off-flavors. “Cut or chop onions as close to the time you plan to use them as you can,” Randle says.

9/23/2013 10:39:02 AM

Help? I am confused. I live north of Seattle so I plant long day onions. I read you can plant them here in October, and other places (including yours) indicate you should plant them 6 to 8 weeks before the first frost (mid October where I am). Can you clarify this discrepancy?

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