In this article, we’ll explore guidelines for choosing a bonsai pot, look at why most trees need a bigger pot in the initial stages of training, and discuss preparing the pot for planting.

The practice of bonsai is an artistic endeavor. It follows that the pot used to house each of these diminutive trees serves a vital artistic purpose. The pot frames the tree and helps set a tone for the overall visual aesthetic. 

Bonsai pots come in a wide range of sizes and colors, plain and textured, glazed and unglazed. With so many choices, it can be a bit confusing for someone just starting out to know how to select the best pots for their early bonsai projects.

From Nursery Container to Bonsai Pot

A beginner’s first bonsai projects typically involve nursery stock or pre bonsai stock grown in a standard plastic nursery pot. Most nursery containers are round and at least as deep as they are wide. Bonsai pots are often rectangular or oval-shaped. With the exception of cascade and semi-cascade pots, they are substantially shallower. 

Most trees just starting training require bonsai pots that are larger than what is considered ideal for the size of the tree. It takes time for new bonsai to develop the compact, fine root structure that will properly support and feed the top growth within a smaller pot. With annual repotting and root pruning, the root ball gradually becomes smaller. This allows the tree to move into successively smaller pots over time. 

Whether you are working with nursery stock or pre bonsai, you should plan how you intend to style the tree before choosing a bonsai pot. Our article about basic bonsai styles can help you with this decision. Then, the guidelines detailed below can assist with selecting a pot that will work well for your tree.

Choosing the Right Bonsai Pot

The art of bonsai has evolved some accepted practices related to matching pots to trees. These guidelines help ensure an aesthetically pleasing union of tree and pot. Let’s break these practices down into three steps and discuss how each step relates to the tree. This exercise will help you narrow down the types of pots to consider for your project.

First, Decide on Shape

When it comes to the shape of the pot, the tree itself and its training style impact what type of pot generally looks best. 

One informal rule of thumb is that heavier-looking trees look best in angular pots, while more rounded pots complement delicate-looking bonsai. Therefore, a rectangular pot would be a perfect choice for a wide-trunked informal upright pine. Conversely, a tall, thin pine trained in the graceful literati style would be better suited to a round pot.

Trees being trained as cascades or semi-cascades require taller pots specifically made for those styles. The cascade pot measures taller than it is wide to accommodate the part of the tree that dips substantially below the pot’s rim.  Trees styled as semi-cascade have branches that run laterally even with the pot’s rim or they dip slightly below the rim.  For this reason, semi-cascade pots tend to be taller and boxier than a regular bonsai pot.

After deciding on the best pot shape, figuring out what size the pot should be is the next step.

Next, Figure Out Size

While the art of bonsai has traditional guidelines for determining the best size for a bonsai pot, trees in the early stages of training will almost certainly need bigger pots than would be considered ideal.

According to tradition, an “ideal” pot would adhere to the following size guidelines:

• A rectangular or oval bonsai pot has a width of approximately 2/3 the height of the tree.
• A round pot has a diameter approximately 1/3 the height of the tree. 
• If the tree’s branch span is wider than its height, the pot should about 2/3 the length of the span. 
• The depth of the pot should be approximately the same width as the trunk at its base. 

Keep in mind that these sizing principles apply to mature bonsai that have spent some time in training. As mentioned earlier, anyone in the beginning stages of training nursery stock, field collected trees and perhaps even pre bonsai will probably need to use a deeper, wider pot for the first few years.

So, how does a beginner pick the right size bonsai pot for a new bonsai-in-training ? By focusing on the tree’s root mass. 

The key to choosing the right size pot is accurately estimating how much of the root ball will remain after the initial pruning. You can then pick a pot that will comfortably accommodate the roots and soil. There are three factors that figure into this equation: The original size of the root mass, the density of the root mass and styling plans for the tree.

Root Mass

If you are starting with either nursery stock or pre bonsai, your plant will most likely be in a round plastic nursery container. These types of pots are generally similar in height and diameter. For example, a “gallon” container typically will be around 6.5” in diameter and 7” tall. 

With the exception of those intended for cascade and semi-cascade styles, the majority of bonsai pots are relatively shallow. Therefore, when you move the plant to a bonsai pot, roots growing vertically in the nursery container will need spread out horizontally in the new pot. Even though you’ll do some pruning, your new bonsai will probably need a pot wider than its nursery container. 

A very general guideline is that, after root pruning, a plant in a container with the dimensions mentioned above will need a pot with inside dimensions in the neighborhood of 8.5” wide by 2.75” deep. Always buy pots based on the inside dimensions. These differ substantially from the outside measurements, and are key to knowing how much the pot will hold.

Keep in mind that you don’t have to stick to the dimensions mentioned above. You could pick a deeper pot with a narrower width, or a wider, more shallow pot. For beginners making the tradeoff between depth and width, it’s always better to choose deeper/narrower over shallow/wider. A deeper pot is easier on the tree, will offer a better visual aesthetic and won’t dry out as fast between waterings.

Root Density

Gently slip the plant out of the nursery pot and take a look at the root mass. Is the plant potbound? If so, the tree will have a larger proportion of roots left after pruning. This will require a slightly larger pot than a tree with a loose network of roots.

The Styling Plan

You will be pruning the roots of the plant during the repotting process. The styling work you do to the top of the plant affects how much you can safely trim from the roots. A couple of guidelines apply to root pruning: 

• It’s generally safe to remove up to 1/3 of the plant’s roots with each repotting.
• The proportion of roots removed can be roughly equal to the proportion of the top growth removed. 

Therefore, if you remove one third or more of the top growth, trim the roots by a third.  If you remove less than a third of the top growth, trim the roots less severely and know that you will need a larger pot.

Now that you have a shape in mind and a general idea of size, it’s time to think about pot colors and finishes.

Finally, Explore Colors and Glazes

The art of bonsai observes traditions with regard to pot colors and glazes. You can decide to follow these guidelines or feel free to go with a less conventional choice!

Evergreen bonsai, such as pines and junipers, are usually placed in unglazed, earthtone pots. Deciduous trees are generally planted in earth-toned pots that might be either glazed or unglazed.  Colorful glazed pots are most often used for flowering or fruiting trees.

When choosing a pot, bonsai practitioners often try to have the color of the pot reflect a color found in the tree. For example, a reddish-brown pot might accentuate a cedar’s red-toned bark, while a deep burgundy pot might pick up a tinge of color in the leaves of a Japanese maple. 

Another guideline is to choose the color of the pot based on the time of year when the tree is at its most beautiful. For flowering or fruiting trees, the selected color often contrasts pleasingly with either the flowers or the fruit. For example, the red berries of pyracantha are pleasingly offset by a green-glazed pot, while the vibrant yellow flowers of forsythia are showcased in contrast with a dark blue pot.

By now, you’ve probably developed a solid idea about size, shape and color for your pot. Now the fun begins – it’s time to start shopping!

Don’t Forget Screens & Wire

In addition to purchasing your pot, you’ll also need to prep it for planting. Therefore, you may need to buy screens to cover the drainage holes on the pot, as well as wire if you don’t already have those supplies. Wire is used to secure the screens in place and also to anchor the tree in the pot. Some pots available for purchase come with screens conveniently pre-installed.

In this article, we’ve looked at choosing a bonsai pot based on the criteria of shape, size and color. We also explored how it takes time for bonsai to develop a fine root mass, and how most trees will need a larger pot in their early years of training.