The bonsai tree is not just one single type of tree, but a wide variety of bushes (including flowers) grown in pots or trays and carefully styled to have the appearance of larger trees in the wild.
They have a rich and long history in both Japanese and Chinese culture and have found popularity worldwide.
Because there are many different kinds of bonsai trees and the fact that they are grown in pots, many people wonder how big they can get.
Bonsai trees are quite a varied bunch, and their sizes and appearances can be just as varied. Read below to find out how small or big they can be, how they grow, as well as how size varies across the different bonsai tree classifications.
Bonsai Tree Sizes vs. Classifications and Types
All bonsai trees are loosely divided into classifications depending on their size, which are as follows: miniature bonsai trees, medium bonsai trees, and large bonsai trees.
Their size and the classification they are placed into are determined by their height and how many people (or hands) are needed to move them.
Miniature Bonsai Trees
Within the miniature bonsai tree classification is the most extensive variety of bonsai trees, which include:
- Kenshitsubo: By far the smallest bonsai at 1-3 inches, this bonsai goes beyond being able to be lifted and moved with a single hand and can actually be moved with a mere two fingers. `
- Shito: Very close in size to Kenshitsubo (sometimes overlapping) is the Shito bonsai. It grows between 2 and 4 inches and can be easily lifted with one hand. Because they are typically grown in pots that are the size of a thimble, they have the nickname “Thimble Bonsai.”
- Shohin: The Shohin’s size of 2-6 inches overlaps with the height of Kenshitsubo, Shito, and Mame bonsais, causing them to be mistaken for these other varieties. One way to tell the difference between them and Mames is the size of the pot they are planted in, as Mame pots tend to be bigger. Additionally, both and Shito and Shohins are pruned with different techniques than the other miniature bonsais.
- Mame: These miniature bonsai trees grow between 4-8 inches. The size difference, as well as the pot, is what is used to tell them apart.
- Kumono: The biggest of the miniature bonsais, the Kumono, is 6-10 inches tall.
Medium Bonsai Trees
In the medium-sized bonsai classification, there are only three types:
- Katade-Mochi: This bonsai might be placed in the miniature classification, as they can be moved with one hand. However, with their height of 10-18 inches, they are a bit too tall to be classified as miniature.
- Chumono and Chiu: These two bonsai are placed under the same name because their appearance and height are similar. The first bonsais on the list that need two hands to move them, they grow anywhere from 16-36 inches.
- Medium and Big: The Medium bonsai grows between 12-24 inches, while the “Big” bonsai is at the top of the classification at a whopping 24-36 inches. They both need two hands to move.
Large Bonsai Trees
Once you reach the large classification of bonsais, the size difference is very noticeable and includes the following four bonsais:
- Omono: Whereas the medium-sized bonsais need two hands to move it, the Omono needs four hands (or two people to move it). It reaches a height of 30-48 inches.
- Dai: These are the same height as Omonos and also need two people to move them.
- Hachi Uye: The second biggest bonsai tree, the Hachi Uye, needs three people to move and is between 40 and 60 inches tall.
- Imperial Bonsai: The largest type of bonsai tree, the Imperial needs eight hands (or four people) to move it and can grow up to 80 inches. They are so named because they can usually only be found in Japanese imperial gardens, with some exceptions.
What Affects the Size of Bonsai Trees?
Many types of trees and plants can become bonsais with proper planting and a specific kind of pruning (even azaleas bushes can be turned into bonsai trees).
When bonsai pruning techniques are implemented, it will naturally lead to the branches and leaves growing minimally. Therefore, it is ultimately up to the grower of the bonsai tree as to how big their bonsai tree will get.
The ways that bonsai growers keep their bonsais small include pruning, potting and root cutting, and growing small leaves.
The first part of keeping a bonsai small involves two kinds of pruning:
- Maintenance pruning: Maintenance pruning is essentially a trim for the tree where you regularly cut smaller branches from the top of the tree during its growing season. This type of pruning encourages the tree to grow more densely and lower to the ground instead of growing taller.
- Structural pruning: Structural pruning involves cutting back branches that are at the bottom of the trees. This includes cutting branches that are too thick, are crossing other branches, are too close to the ground, or just generally not conducive to the style of bonsai you are trying to grow.
Repotting and Root Cutting
A big part of keeping bonsais at a specific size is to grow them in appropriately sized pots. As in, if you want to make sure your bonsai stays small, keep it in a small pot.
However, you can’t just leave it in a pot without a little extra maintenance. That’s where repotting and root cutting come in.
The best way to tell if it is time to repot a bonsai is to check the drainage holes. If roots are poking through, that is an indication that it has outgrown the pot. From here, you have two choices.
If you want to keep the plant the same size, you will put it back in the pot you took it from after doing the following:
- Push the tree out of the pot from the bottom.
- Clear off any rocks, dirt, or anything that is not part of the root.
- Trim the roots in such a way that they form a radial shape.
- Spray the roots lightly with water, so they don’t get dry.
- Place the tree back in the pot and make sure that you’ve trimmed the roots enough that they are no longer touching the sides of the pot.
- Take the tree back out of the pot, fill the pot halfway with soil, place the bonsai back in, and fill up the pot the rest of the way with soil.
Suppose you want the tree to continue getting larger. In that case, you will follow all the same steps above (keeping the root trimming to just maintain the radial shape and removing any wayward or awkwardly growing ones), then put the bonsai in a larger pot.
Keeping the Leaves Small
Having a small bonsai means having small leaves to go with the small stature. There are several ways to grow small leaves:
- Pick a small-leafed plant such as an oak.
- Keep it in an area with lots of sunlight. Leaves grow bigger when they are in a dimmer area because they are “reaching” for the sun.
- Remove the first leaves produced. The ones that grow in after will be smaller.
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Bonsai trees come in all sizes, from miniature bonsais at just an inch to Imperial bonsais at 80 inches. Bonsais are loosely classified by miniature, medium, or large sizes.
To keep bonsais small, regular pruning, repotting, and root cutting are necessary. It is also essential to keep the leaves small to work well with the bonsai’s relatively small height.
This can be done by picking a plant with naturally small leaves and placing the bonsai in an area with lots of sunshine.