Are Onions Vegetables? – Everything You Need To Know

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One of the most important staples in your kitchen pantry should be a bag of onions.

Regardless of whether you prefer red, white, yellow, sweet, or even shallots, these bulbs offer an opportunity to layer flavor in raw and cooked dishes. They are also amazing when pickled. 

The uses for onions in the kitchen are virtually limitless, and they can take your dishes that are just fine to “holy-moly-that’s-DELICIOUS”.

Especially if you learn how to properly caramelize your onions for the best flavor. Thanks to their sweetness, you may be wondering whether onions are fruits or vegetables.

So, are onions vegetables? Onions are botanically classified as vegetables. Specifically, they are the bulb of the allium plant that grows underground. 

Keep reading to learn the botanical difference between fruits and vegetables, why onions are classified as a vegetable, some great varieties of onions to experiment within the kitchen, and a list of fruits that pretend to be vegetables. 

Are Onions Fruits Or Vegetables?

To define a plant as a fruit, it needs to be identified as the ripened ovary of the plant. Often this ovary grows out of a flower blossom and matures into the edible fruiting part of the plant. These ovaries contain the seeds that are required for the fruit to reproduce and create more plants. 

An easy rule of thumb to decide if food is a fruit or a vegetable is to check to see if it has any seeds. If there are visible seeds, then chances are it is technically a fruit.

Based on this definition of a fruit, onions are not fruit. While some onions may be slightly sweet to taste, they do not contain any visible or edible seeds in the part of the plant that we are typically eating. 

The seeds come later, after the plant bolts. This happens when the plant turns its focus to seed production, usually when the weather cools. At this point, a central stalk will start to grow taller. If it remains in the ground it will flower and produce seeds so that you can grow more onions. 

What Makes An Onion A Vegetable?

Onions are vegetables because they do not contain edible seeds and are not made of the ovary or fruiting body of the plant designed for reproduction.

Onions are allium vegetables, which technically means they can be classified as an herb.

When trying to define a vegetable, it is a broader category than fruits because they can be made up of so many parts of the plant. A good way to figure out if something is a vegetable is to exclude it as a fruit. 

That means looking at whether it is the specific ovary or the fruiting body of the plant designed for reproduction. Does it contain edible seeds? If you answer no to these questions, then chances are you’ve got a vegetable on your hands.

When classifying vegetables, they can be stalks, such as rhubarb and lovage. You can also have vegetables that are made of leaves, like cabbage and lettuce.

Some of my favorite vegetables are fall root and tuber vegetables like potatoes, sweet potatoes, carrots, and beets. 

Other vegetable classifications include asparagus, which would be a stem, and vegetative or flowering buds that include things like Brussels sprouts, broccoli, and cauliflower. 

If you think about all of these vegetables, none of them contain seeds since they come from another part of the plant. Onion bulbs can be used to plant and grow new onions without the need for pollination or seeds.

Are Onions Root Vegetables?

Onions are not actually the root of the plant. They are actually a tunicated bulb that stores energy for the plant.

Onions grow underground like some of our favorite root vegetables such as potatoes, sweet potatoes, beets, carrots, turnips, beets and radishes

The tunicated term comes from the papery “tunic” that covers the rest of the bulb. That’s what we would refer to as the skin of the onion. 

Many of the plants we refer to as root vegetables are corms, tubers, tuberous roots, or rhizomes that are all slightly different from the bulb that makes up members of the onion family. 

Are Onions Nightshade Vegetables?

Onions are not in the nightshade family. Nightshades contain a tiny amount of alkaloids, which are components that contribute to the bitter flavor of nightshade vegetables.

Onions get their flavor primarily from sulfuric compounds.

What Other Vegetables Are Onions?

Onions are one of my favorite kitchen staples since they can help layer so much flavor into any dish that you’re making.

While you might be most familiar with the standard white or red onions, there are other varieties out there that have unique flavors and textures. 

bundle of chives isolated on white background

If you want to take your recipes to the next level, give some of these onions a try. 


These flavorful little herbs are bulbous perennials related to onions.

They are part of the allium family and have a delicate flavor, which makes them perfect for thinly slicing and using as a garnish on eggs, soups, and other dishes. 

Green or Spring Onions

bundle of green onions isolated on white background
Spring onions

I love using these onions in stir-fries or raw on salads and other dishes.

They have a slightly stronger flavor than chives, but nothing overwhelming.

Make sure you eat the white bulb part too since that’s where most of the flavor lives. 

three shallots isolated on white background


I adore shallots. They are delicious raw or cooked.

These pink beauties crisp up nicely if you want to dust them in a little flour and shallow fry them to use as a garnish on dishes.

They are small, pinkish/purple, and have a slightly sweeter and milder flavor than red onions.

small bowl of pickle white pearl onions
Pickled pearl onions

Pearl Onions

These mini onions are firm, juicy, and crisp with a slightly savory-sweet flavor that is less intense than white onion.

They are perfect for pickling. 

Yellow Onions

yellow onion isolated on white background
Yellow onion

This variety of onions is likely the most common you will see in the store.

They are great in most recipes and especially if you want to caramelize your onions. They have a mild, slightly sweet flavor. 

White Onions

three white onions isolated on white background
White onions

You are most likely to find these onions in things such as potato or pasta salad and traditional Mexican dishes.

They have a strong flavor and can add a slight sweetness to their dishes. They are great raw. 

Sweet Onions

Sweet onions are perfect to use in relish, as a tasty garnish, or to add a pop of sweetness to your salad.

Vidalia sweet onion isolated on white background
Vidalia sweet onion

They have a lovely mild onion flavor with a touch of sweetness. Some of my favorite sweet onions include Vidalias, Walla Wallas and Mauis.

Red Onions

I love red onions because of their reddish-purple coloring and their sweet, pungent taste.

red onion chopped in half
Red onion

I throw them in raw dishes like salads, but they’re also amazing in rich tomato-based curries.

Try pickling or grilling them for an extra special treat. 

What Vegetables Are Actually Fruits? 

While you may have wondered whether onions are vegetables, you might not know that based on the above botanical definitions some of the most popular vegetables that grace our dinner tables are actually classified as fruits. 

  • Avocados contain one large seed in the center of the fruit. Even though they are used in savory dishes, avocados are fruits.
  • Olives have a fleshy outside that surrounds the seed. This is another super savory “vegetable” that is a fruit in disguise.
  • Tomatoes when cut in half and you will find tomatoes are full of seeds ready to create a whole new plant. Most commonly they are used in savory dishes, though they pair well with sweet balsamic and honey. 
  • Cucumbers. Like tomatoes, cucumbers contain seeds inside. I’m not a fan of the texture of cucumbers, but one of the best ways to enjoy them without the sliminess is to cut them in half and scrape out the seeds and gel that surround them. 
  • Zucchini and other summer squashes. If you take a peek inside and you will find tons of little seeds waiting to become brand-new summer squash plants. 
  • Butternut squash, pumpkin, delicata squash, and other winter squashes. The seeds in these hearty squashes taste delicious when roasted with olive oil, pepper, and sea salt for a perfect seasonal fall treat.
  • Eggplants. The soft center of the eggplant surrounds seeds. I love roasting my eggplant to make a baba ganoush dip.
  • Peppers. The best way to remove the seeds from inside a pepper is to cut off the top where the stem is, reach in and scoop out the middle, then tap the pepper against your hand to remove any last seeds. You can trim the flesh from around the stem and use that too.
  • Okra. The mucilaginous inside of okra surrounds the seeds needed to grow new plants. 

You might have noticed a theme on this list of fruits pretending to be vegetables. Take a look inside and you’ll see they all have seeds.

So if you’re ever curious whether food is a fruit or a vegetable, a general rule of thumb is that if it has seeds that help the plant reproduce, then it is a fruit. 

What To Do With Onions

Below are a couple of ideas for using up your onions.

Caramelize Sweet Onions

The key to perfectly caramelized onions is time and patience. You don’t want to rush the process or you could end up with onions that are charred on the outside and still crunchy in the middle.

This style is also delicious, but not the same effect that you’re going for when you caramelize. 


  • 4 white, yellow, or sweet onions, peeled and thinly sliced
  • 1-2 tablespoons of salted butter 
  • 1/2 teaspoon sea salt
  • 1 tablespoon white sugar, maple syrup, or honey 
  • Optional: 1-2 teaspoons balsamic vinegar


  1. Place a large frying pan or skillet on the stove over medium heat. 
  2. Let it warm up, add the butter and let it melt. 
  3. Once the butter is melted, add your onions. Take the time to break them apart as you add them to the frying pan for even cooking results. 
  4. Add the salt and sugar, maple syrup, or honey to the frying pan.
  5. Stir the onions, so they are fully coated in butter and sweetener, then turn the heat down to a medium-low.
  6. Place a lid on the onions and let them cook until soft and gently browned. You will want to stir them every 3-5 minutes. After about 10 minutes you can add the balsamic vinegar and stir to coat the onions. Continue cooking.
  7. This could take up to 30 minutes. Be patient! The flavor is worth it. 
  8. Once fully caramelized, remove from heat and serve. 

Pickle Red Onions

Adding pickled red onions to tacos and other dishes is a great way to give your meal a fresh, bright hit of flavor. Try this quick pickle recipe to take your next meal to another level. 


  • 1 red onion, peeled and thinly sliced
  • 1 clove of garlic, minced 
  • 1/4 cup sugar or maple syrup
  • 1.5 teaspoons salt
  • 1/2 cup red wine vinegar 
  • 1 lime, juice and zest 
  • Water to cover 


  • Add your thinly sliced red onion to a medium-sized mixing bowl.
  • Stir in the garlic, sugar, and salt until fully coated. You can gently mash them with a wooden spoon to soften the onions and garlic a bit.
  • Add the red wine vinegar, lime zest and juice, and enough water to just cover the onions. 
  • Give the mixture a stir and press the onions to soften them more.
  • Let the mix sit at room temperature for about an hour before enjoying them. You can then transfer your leftovers to a clean mason jar.
  • Place the pickled onions in the fridge and use them within about 2-4 weeks. 

You can get creative with this recipe by using other types of vinegar such as apple cider, white wine, or rice vinegar.

You can also add herbs like cilantro and green onions to the mix for even more flavor. And if you like spice, add a sliced jalapeno. 

When it comes to pickled onions, the options are limited only by what you have on hand and your taste buds, so enjoy experimenting until you find your perfect pickling recipe. 

Up Next: 11 Best Malt Vinegars

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