Grocery Guides

Sweet Onions – All You Need to Know | Instacart Guide to Fresh Produce



Last Updated: Aug 3, 2021

What are sweet onions?

With sweet onions, the name says it all. They are onions that add lots of flavor without the strong flavor of other onion varieties. Even those who don’t usually like onions because of the bite enjoy sweet onions. Some common sweet onions include Vidalia onions, Walla Walla onions, Texas sweet onions, and Maui onions.

Sweet onions are used in many recipes, including onion rings and caramelized with cuts of meat. They are often used for dips, jams, and salad dressings, as well. They are just as complementary to cold, summery dishes as they are to cooked winter soups and dishes.

Where did sweet onions originate from?

Sweet onions have been cultivated in many places, with the earliest known location being the Bermuda Islands. In 1898, they were brought to Texas, which is now the top producer of onions in the United States.

There are a few special varieties of sweet onions, including Vidalia onions and Walla Walla onions. Vidalia onions have been cultivated since the 1930s and derive their name from their place of origin, Vidalia, Georgia. Only the onions that grow within a designated 20-county area are authentic Vidalia onions and allowed to be sold as such.

Walla Walla onions are a large sweet onion from Washington state. They were developed by local farmers in the early 1900s and also named after the town from which they come.

What is the nutritional value of sweet onions?

Sweet onions are mostly water, fiber, and natural sugar and low in calories, which means you can enjoy them guilt-free on top of salads, soups, and sandwiches.

A medium-sized sweet onion contains:

  • 60 calories
  • 0g fat
  • 1g protein
  • 3g fiber
  • 16g carbohydrates

Sweet onions are rich in vitamin C and also contain vitamin B6. They have folate, potassium, magnesium, thiamin, and manganese.

How are sweet onions grown?

Sweet onions need lots of sun, good soil, and frequent watering. They are best planted in spring and can be done from seeds that you start indoors or directly in the ground. Onions do well in both a traditional garden and raised beds.

They need to be planted 1in deep and about 6in apart. You should water them daily until they begin to germinate and then switch to once or twice weekly waterings. Onions require lots of nitrogen, so using a nitrogen-rich fertilizer every 2 weeks is ideal.

Sweet onions take 3 to 4 months to mature and be ready to pick. You’ll know they are ready for harvest when you start to see the onion bulbs emerge from the earth and the tops fall over. Stored properly, they will keep for several months.

When are sweet onions in season?

Sweet onions are generally planted in April and ready for harvest between August and September. They can be grown year-round in southern climates, supplying fresh sweet onions all year long.

Special varieties like Vidalia onions are only grown during the summer months. They are typically available through December, thanks to climate-controlled storage.

How do you pick sweet onions at the grocery store?

Sweet onions should feel firm and heavy for their size. There should be no bruising or spots on them. Black spots quickly turn to mold, so avoid any onions with spots.

Don’t forget; you can share these tips with your Instacart shopper to ensure you get the freshest sweet onions available. Just leave a note when you place your order.

How to store sweet onions

Sweet onions can be kept in a cool, dry, and dark place like a pantry or basement. They will keep for several months, but if you notice them sprouting, this is a sign that they will soon go bad.

Peeled but whole, sweet onions can be stored in the refrigerator for up to 2 weeks. Wrap them in paper towels and store them in the produce drawer with the vent closed.

Cut or sliced uncooked onions should be stored in airtight containers and refrigerated for no more than 3 days. Cooked onions will last up to 7 days, but always use as soon as possible and throw them out if you have any question about their freshness.

Sweet onions can be frozen for up to 12 months. Peel, wash, and cut the onions and freeze on a flat pan or cookie sheet until solid. Place onion pieces in a well-sealed container and use them as needed.

How to tell if sweet onions are bad

Before sweet onions go bad, you may notice that they begin to sprout or develop black spots. They become soft and develop mushy spots, which quickly ruin the entire onion.

If they begin to emit a foul odor, you can be sure they’ve gone bad. The same applies to cut onions in the refrigerator. Once they’re past their prime, they become slimy and start to smell.

What can I substitute for sweet onions?

Sweet onions are unique in that they have a very mild, sweet flavor that is quite different from its cousin, the red onion. When you need a sweet onion but don’t have any, white onions, yellow onions, or shallots make a suitable substitute.

Save time and money by ordering sweet onions in bulk

Whether you want a mild yet crunchy onion to add to your burgers and salads or want to try your hand at making onion rings, sweet onions are a great kitchen staple to have on hand at all times.

Save time by shopping sweet onions with Instacart, so you never run out. It takes just minutes to place your order online, and you can pick it up in-store within 2 hours or get same-day delivery.



Instacart is the world's largest online grocery service with over 500 million products available from 40,000 stores. To read more Instacart posts, you can browse the company blog or search by keyword using the search bar at the top of the page.

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