Asymmetry is an essential element in any Ikebana flower arrangement, reflecting the strength and weakness, light and darkness of nature.
Design education often includes a rule that elements should be symmetrical because people find this more attractive, but this is not necessarily true. People find balance attractive and calming. Balance is most easily achieved with symmetry, a technique that uses mirror-like elements that are the same on opposite sides.
Asymmetrical balance is an alternative to symmetry that is far more difficult to master. It relies on a composition balance of dissimilar elements as opposed to a simple mirroring effect.
Designs which are asymmetrical are more dynamic, active, and invite the viewer in to participate. An asymmetrical design will lead the eye more and stimulates the viewer to explore and interpret the content. Asymmetrical designs may evoke a sense of flow or movement and gives a more modern feeling than a symmetrical design. It's important to remember that harmony is key and can be achieved in an asymmetrical design when care is given to achieving balance among the elements.
Asymmetrical balance occurs when you have different visual images on either side of a design, and yet the image still seems balanced. To be considered asymmetrical, a design needs to have unequal visual weight on either side, but those unequal visuals need to balance each other. Therefore, no part of the composition should mirror another one.
In an Ikebana arrangement there are three main branches which are positioned in a asymmetrical or scalene triangle. To create a successful asymmetrical design, you still need to figure out how to balance out the arrangement. Careful thought is given to the height of the first main stem and placing of the main flower creating an impact. In addition a balance of 30/70 should be achieved as opposed to a 50/50, meaning that the principal elements should be either centered around the left or the right hand side of the composition, which is indicated in the below image :-
image http://keithstanley.com/tag/moribana/
This is the very first lesson in Sogetsu Ikebana known as the Basic Upright style Moribana. The three main stems are placed in precised positions on a Kenzan - both Shin and Soe are slanting towards the left hand side while Hikae is positioned on the right. The three stems are placed in a triangle on the Kenzan with Shin at the top of the triangle at a 10-15 degree angle, Soe placed bottom left of the triangle at a 45 degree and Hikae bottom right of the triangle at 75 degrees. These principal branches also have a strong forward movement in the arrangement producing the asymmetrical pattern. This allows your eye to travel from the top of Shin to Soe and rests on Hikae as if a breeze from nature was sweeping through the arrangement.
Mother Nature is far from symmetrical and creates all sorts of patterns and shapes. No two trees are alike, no roots follow the exact same pattern, and no natural surface is even. Nature is full of surprises where perfection and symmetry do not occur naturally. Asymmetry, odd numbers, irregularity, unevenness, imbalance conveys the natural world, and it brings about the idea of maintaining balance and harmony.
Human beings are not symmetrical or perfectly aligned, life in all its imperfections is beautiful. Embrace asymmetry!
https://blog.hubspot.com/marketing/asymmetrical-balance
https://harshforms.com/ikebana-asymmetry/