How Big Can Bonsai Trees Grow?

Bonsais are famous for being small, but what does “small” actually mean? 

And when does a bonsai stop being a bonsai?

Bonsai trees come in an enormous range of sizes, and their owner usually dictates their height by choosing what kind of container to put them in. 

Overall, bonsai trees can range from several inches tall to over six feet (2 m).

Yet, trees over 80 inches (203 cm) are no longer bonsais. 

In this article, we’ll look at how large a bonsai can get as well as size classifications and how to get your bonsai to the height you want. 

How Large Can a Bonsai Tree Be?

If you follow the official regulation, a bonsai tree cannot be larger than 80 inches (203 cm).

Trees bigger than this can not compete in competitions. 

You also technically shouldn’t refer to them as bonsais as they are too big. 

Instead, they are just small trees, and although some people mistakenly refer to them as bonsai trees, they are not in the same category.

However, there is no lower size limit on bonsai trees. 

A plant can be absolutely tiny and still count as a bonsai tree.

Some people, in fact, will grow a bonsai in a pot the size of a large coin, and this still counts as a bonsai. 

So, bonsais can be as small as nature will allow.

But, if you let your bonsai get too big, the official classifications will no longer see it as a bonsai. 

How Do People Keep Bonsais Small?

People can keep bonsais small by tightly restricting their roots in a small container. 

A tiny pot will keep the tree from growing quickly. 

Thus, gardeners deliberately choose containers that will prevent the tree from spreading its roots, tapping into lots of nutrients, and shooting up.

So, the tree stays small throughout its life.

Gardeners also prune the roots and stems of the plant as it grows, keeping it small and maintaining the desired shape by simply removing growth that doesn’t fit with the tree’s aesthetic.

Without this root restriction and pruning, the bonsai would reach the same size as any other tree of its species. 

They would grow tall under normal circumstances because bonsai trees have not been genetically altered or modified in any way that prevents them from reaching this kind of height.

It is, therefore, crucial to choose a container that will prevent the tree from branching out and expanding if you wish to keep it to the proper size for a bonsai.

Thus, many people have containers handmade to suit their specific trees, which ensures that the container is exactly the right depth and width for the tree they wish to grow.

However, you can use any small container to keep the bonsai at the desired size and shape.

What Are the Size Classifications for Bonsai Trees?

You might be surprised to learn that every bonsai size has its own category. 

And there are a great many categories.

Yet, the three overarching classifications are miniature, medium, and large.

The tree sizes within the miniature category include:

• Keshitsubo, between 1 and 3 inches (3-8 cm). 
• Shito, between 2 and 4 inches (5-10 cm). 
• Mame, between 2 and 6 inches (5-15 cm). 
• Shohin, between 5 and 8 inches (13-20 cm). 
• Komono, between 6 and 10 inches (15-25 cm). 

In the medium bonsai category, you will find:

• Katade-Mochi, between 10 and 18 inches (25-46 cm). 
• Chumono/Chiu, between 16 and 36 inches (41-91 cm). 

In the large bonsai category, there are:

• Omono/Dai, between 30 and 48 inches (76-122 cm). 
• Hachi-Uye, between 40 and 60 inches (102-152 cm). 
• Imperial, between 60 and 80 inches (152-203 cm). 

Classifications can be more complicated than this list indicates, though, because there is overlap between the categories. 

Also, the category names sometimes refer to the growing style as well, which can muddle things further. 

However, this list should give you a starting point for understanding the different kinds of bonsai trees and how their sizes work.

Why Are Some Bonsai Trees So Large?

You might be wondering why bonsai trees can get so big. 

The largest categories are sometimes known as eight-hand trees because four people are needed to lift just one of them.

That might seem at odds with the idea of creating a tiny, miniaturized tree, so why do bonsais get this big?

In the past, a large bonsai was a status symbol, and emperors and other royalty usually owned these trees to show off their wealth.

And wealthy people sought out these huge trees because it takes a long time to get a bonsai to this size. 

So, large bonsais were, and still are, expensive. 

Owning one was, therefore, a good way to demonstrate power and wealth. 

How Do You Get a Bonsai to Grow Taller?

Getting a bonsai to grow taller is a tricky balance because the tree needs more space to get large. 

But, if you just put it in an enormous container, it may grow far too tall.

Instead, you’ll need to re-pot your bonsai several times so that you can contain its growth each time. 

You will also have to provide the best possible conditions by regularly watering, feeding, and pruning your tree while ensuring it has plenty of light. 

Additionally, you will need a lot of patience if you wish to grow a tall bonsai, as it often takes 15 years or so for them to reach an impressive size. 

In many cases, it can take up to 40 years for a seed to grow into an Imperial bonsai.

Thus, you will have to have lots of dedication, patience, and hard work to grow a tall bonsai. 

Conclusion

Bonsai trees can grow up to 80 inches (203 cm) before they aren’t bonsai trees anymore. 

Yet, on the whole, bonsai trees are below 67 inches (170 cm) in height, and many are far smaller.