A widely accepted principle within the art of bonsai is to prune and style the top growth in a triangular shape. This article explores the whys and hows of applying this concept to bonsai styling decisions. 

When I first started in bonsai, one of the most challenging aspects for me was styling the top growth. Other facets of the hobby such as root pruning, picking a front view, choosing a style and deciding on a pot seemed easy to master. 

However, I felt lost and nervous when it came time to shape the foliage. Knowing what parts to trim and what parts to leave was always a struggle. After my trimming efforts, I’d be happy with some trees, but others didn’t look quite right. 

Things finally came together for me when I learned about the simple concept of using a triangle shape to guide the tree’s design. I found this foundational technique immensely helpful, both for visualizing a pleasing end result and for acting as a guide for trimming the top growth.

A Quick Triangle Geometry Review

As we all learned in school, a triangle is a shape that has three sides and three interior angles. The lengths of two of the sides must add up to a number greater than the length of the remaining side. The three angles always add up to 180 degrees.

Variations in the lengths and angles define the three major types of triangles:

Equilateral triangles have three equal sides and three equal angles.

Isosceles triangles have two equal sides and two equal angles. The two equal sides meet at a point to form the unique angle. The non-equal third side forms the base of the triangle. Where the base joins the other sides, it forms the two equal angles.

Scalene triangles feature no equal sides and no equal angles. The countless possible combinations of unique side lengths and unique angle values mean that scalene triangles can vary widely in how they look. Some might resemble a slightly “off” equilateral or isosceles triangle, while others with wide variations in sides and angles look sharp and exaggerated.

How Does the Triangle Apply to Bonsai?

Interestingly, the triangle shape mimics how trees usually grow in nature. The older bottom branches are generally bigger and longer than the younger branches higher up in the tree. This natural growth pattern allows all parts of the tree to receive sunlight.

From a visual perspective, the triangle lends balance, stability and interest to the overall design. It settles the eye and frees it from having to focus on disparate elements in order to absorb the whole.

Triangles and Tree Styles

Before applying the triangle in tree design, the first tasks are determining best the front view and deciding on a bonsai style. Explore our articles to learn more about basic and more creative bonsai styles.

Sometimes the tree is a formal or informal upright style. Both the equilateral or isosceles triangle have two matching base angles and provide a symmetrical, tapered result perfect for a more stately presentation.

Conversely, a more dramatic scalene triangular form with major differences in side lengths and angles would be a fitting way to style a sparse, meandering literati tree.

When it comes to designing bonsai, the scalene triangle offers hobbyists a great deal of flexibility. It adjusts to accommodate a variety of possible styling choices. It can function as a simple template to guide trimming for an already well-designed tree, or it can help plan a radical reduction and shaping of new material.

Using a Triangle in Bonsai

When applying the triangle concept to styling bonsai, the longest side, or base, of the triangle is represented by the widest span of the tree. Typically, that base runs the combined length of the primary and secondary branches.

The primary branch is the lowest, longest and thickest branch on the tree. It is generally located about one third of the way up the trunk, on either the right or the left side. The secondary branch is somewhat shorter and thinner. It occurs above the primary branch on the opposite side of the tree.

With the primary and secondary branches forming the base side of the triangle, the other two sides stretch from the endpoints of the base to meet at the apex, or highest point of the tree.

Keep in mind that the base of the triangle can tilt to accommodate the effects that bends, curves, or cascades have in the overall design.

When envisioning the design of a tree, bonsai practitioners have flexibility in choosing the primary and secondary branches, the length of those branches, and which part of the tree forms the apex. The triangle concept can assist with these initial design decisions, as well as the finer styling choices that come next.

Prune Loosely to Shape

After determining the primary and secondary branches and the apex, prune and/or wire to establish their positions. With the points of the triangle now set, it’s time to prune to shape.

It’s very important to think of the triangle as a general guideline, rather than as an exact template to follow. Trimming should focus on making the foliage look natural as opposed to conforming tightly to the triangle.

It turns out that, to the human eye, a loosely interpreted triangle is equally effective as a tightly structured one.  This means that there could be some voids in the triangle shape. Also, some parts of the tree might fall outside the lines. The result will be a natural-looking but still visually effective tree design.

When working with bonsai styles featuring more than one trunk, the combined foliage of the composition as a whole is trimmed to a triangular shape. In styles with multiple individual trees, each tree is generally styled as a triangle within the larger overall triangle.

This article explored how using a triangle concept can help with design and styling of top growth in bonsai. The triangular shape imparts balance, stability and interest into the overall composition.