Is Onion a Root Vegetable? – You Need To Know This!

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Last Updated on September 18, 2022 by Griselda M.

Onions are an entirely unlikely vegetable crop. Whoever dug up the first onion and thought “wow, I love this pungent bulb that makes me cry, let’s grow more of them” was a brave and confused individual indeed. 5000 years of cultivation later, this brings us to answer your question “Is onion a root vegetable?”. 

What is an Onion?

We have all seen onions, and in many cases, tried to grow them! Sometimes successfully. An onion, or Allium cepa, is a cultivated bulb.

The leaves are hollow. During the growth cycle, typically a seed germinates, the seedling grows for one season at the end of which the plant forms a little bulb that then overwinters, and in the second season this bulb will then grow, and the plant will go into flower and produce more seeds. In my experience, I always manage to somehow get things to flower in one season, which is frustrating. The area I am in is really bad for onion cultivation.

Onions have a few closely related species that are important to us as well, such as leeks, chives, and garlic to name a few. Onions are one of the older cultivated plants oddly enough with a history of cultivation that is at least 5000 years, probably a lot more.  When cooking many dishes around the world, the food just does not taste right without an onion – oddly enough this leads to onion riots in India!

There are many different cultivars of onions – my favorite being the red and purple types such as this.

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Onions are very healthy root vegetables – they contain a range of beneficial vitamins, minerals, and phytochemicals that enhance our health and improve our immune systems, and circulatory systems, protect our brains, and generally make life better.

What Are Root Vegetables?

The definition of a root vegetable is simple – a plant part that is formed under the soil that is eaten as a vegetable. Most root vegetables are storage organs that plants form to allow them to survive harsh conditions such as winters and dry seasons. There are a few definitions, but they all mean the above.

Different types of root vegetables

There are many ways a plant can store nutrients under the soil. Let’s have a look at these:

A root tuber

Is an enlarged storage root – a good example is a carrot, beetroot, or parsnip.

A stem tuber

This is an enlarged underground stem. The classic example is a potato.




These often look like bulbs, but if you cut them, you will see that they do not have layers like a bulb. Whenever I go to Mauritius I enjoy eating Taro corms. These are special treats. But they need warm tropical conditions to grow.


These are underground creeping stems for want of a better description. Normally a stem grows up – a rhizome is a stem that grows underground, or on the surface and sends up shoots and sends down roots. They can be storage organs. A good example is a ginger rhizome.

Learn more about Got Onion With Stem. Here 3 Great Ways To Use It

Is onion fruit or root

Is Onion a Root Vegetable?

Is Onion A Root Vegetable? Well, we see that it is a bulb, and if you eat a bulb, it is a root vegetable as per the definitions above. The really important thing about an onion, in terms of our health, is that it is a storage root vegetable.

Onions accumulate several important minerals, including Iron, Potassium, and Calcium that are essential to our health. This is why this humble root vegetable is so important to so many different cultural cooking styles around the entire planet.

A Few Tips On Growing Onions At Home

There are two ways to grow onions – from seeds, or small onion bulbs or sets. Onions thrive in sandy soil rich in organic matter, but you can grow them in nearly any soil. I have grown them successfully in poor clay, sand, loam, and once in compost!!

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I typically start my onion seed bed by planting the seed straight into the ground. I use a rich sieved loam for this. Water the seed bed every two days (if needed) until the seeds germinate. Once they germinate I typically let the shoots grow to 5-6 inches in length.

I prepare the main growing bed so that it is rich in organic matter, but not manure. The soil should be quite soft and friable. I then use a small dibbing stick to make holes in the ground and drop the onions into the holes.

If you want small onions plant them a few inches apart, and if you want giant onions plant them about 5-10 inches apart depending on how much space you have. The further they are apart the bigger the onions. This will naturally depend on the cultivar.

If you have never grown onions before, start with Texas Grano. This always delivers.


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If you decide to go with small onion bulbs (sets) you can plant these about two inches deep in the soil, and they will sprout and push through. I do not plant them deeper than this in my area as this encourages the mole rate to eat them. If you do not have mole rats consider yourself lucky.

Conclusion On The Question “Is Onion a Root Vegetable?”

Yes, it is. I hope you enjoyed this little sojourn through the history and botany of the onion. As a final little aside tip – many of us have had the problem of onions sprouting – if this happens to you, buy a few pots, put some decent potting soil in them, plant the sprouting onions and you can harvest the leaves for a month or two before the onions go into full flower!

Now and then you may be lucky and the onion may decide not to flower and in this case, you will get a huge onion. I once did this and harvested an onion that weighed close to a pound!!


Are onions and garlic root vegetables?

Yes they are. They are underground storage organs of plants, and are eaten buy humans, therefore they are root vegetables.

Is onion fruit or root?

An onion is a bulb. It is not a fruit. You can try and bite into it like an apple, but the result will be character building.

What type of vegetable is an onion?

An onion is a bulb. It is an underground storage organ of the onion plant, Allium cepa (excuse the lack of italics - we cannot use them in this section of the program).

What vegetables are not root vegetables?

If you harvest a vegetable from above the soil, it is not a root vegetable. As an example, a cabbage is not a root vegetable. A carrot is a root vegetable.

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