The word bonsai consists of two kanji characters. The first of these symbols is 盆 (bon), meaning "tray" or "container," followed by 栽 (sai), which means "to plant." In other words, bonsai can be loosely translated as "to plant in a container." Simple enough, but why then do we not consider every container grown plant as a bonsai? What is it that delineates bonsai art from other similar horticultural practices? 

Perhaps, then, there is some broader element of artistic or aesthetic practice that can be employed as a distinguishing factor. 

While this certainly narrows the field of view, it fails to eliminate other areas of ornamental horticultural practice, including niwaki, topiary, espalier, etc, which also utilize aesthetic design principles applied to living plant material. In fact, many of these principles are directly translatable for use in bonsai culture, particularly those applied to Japanese niwaki, or garden trees. One need only visit Ritsurin Park in Takamatsu or Tenryu-ji in Kyoto to see these similarities in design and to appreciate the practical diligence of centuries of applied technique.

Maybe, then, there exist narrower, more specific design parameters that provide a foundation on which to define the term. 

This, however, is a rather treacherous road to traverse. Again, not only are many of the design principles utilized in both garden trained and container-grown niwaki nearly identical to those applied in bonsai, but creating specific design parameters necessarily stifles artistic expression and will inevitably limit our later ability to persuade others of the value of bonsai as art.

One common assertion in defining bonsai is that they must be small. Well, how small? Are there any limits to the size of a bonsai? In the contemporary Japanese context, there are in fact size limitations in bonsai, particularly for trees exhibited at the Kokufu-ten, or Japanese National Exhibition.  But are these size regulations necessarily applicable to all bonsai in all contexts?  To understand why these size limitations are in place at the Kokufu-ten in Japan, and whether or not they should apply more broadly to bonsai art, let’s take an in-depth look at the exhibition.

The Kokufu-ten, held each February at the Tokyo Metropolitan Museum in Ueno, is the world's most prestigious annual bonsai showcase. Exhibited trees must fall within the specified size ranges of any of three classifications. Shohin bonsai are those measuring up to 20cm in height from the upper lip of the pot to the highest point on the tree. These are usually displayed in groups as five or seven-point arrangements. Chuuhin bonsai range in size from about 35 to 50cm in height, measured in the same manner. These are typically displayed in a three-point arrangement with a single Shohin bonsai and an accent plant. The last category is that of Ogata bonsai, which mostly range in size from 60 to 100cm (1m). These categorical size ranges are in place at the Kokufu-ten for two specific reasons - to aid in the judging process and the issuing of awards, and to guarantee overcrowding does not occur in the limited available space of the museum. But this says nothing about size limits as a defining factor of bonsai in general. In fact, there are numerous examples of bonsai with heights well beyond 1m, both in famous nurseries and in the Imperial collection in Japan, and in the gardens of artists and professionals around the world, including in Vietnam, China, India and across Europe. While these extra large examples may be in the minority, with most bonsai situated between 10cm and 1m in height, this in no way excludes them from falling under the purview of bonsai art.

Can, then, an argument be made for a species-based definition of bonsai? In other words, can we narrow the field by eliminating certain species for inclusion as bonsai?

One will often hear the question from the uninitiated, 'is bonsai a species of plant?' to which the answer is of course, no.  Any plant can be utilized as a bonsai, so long as its leaves can be reduced in size to appear in proportion with the small size of the tree.  It is also often asserted that species used for bonsai must be those with woody trunks. While these traits might make the development of aged-looking trunks and fine branch structures easier and quicker to attain, they are not intrinsic to the definition of bonsai. Bonsai is a dynamic art in that both subjective and objective elements must be weighed against each other in the creation and development of each piece. For example, if the subjective value judgement is that fine branch ramification is desirable, then an objective decision can be made about the ways to achieve that outcome. In such a case, selecting varieties or cultivars of species with smaller leaf sizes and nodal distances (in addition to the employment of proper horticultural techniques) will help one better, and more quickly, reach that end goal. However, if one places greater emphasis on the enjoyment of fruit or flowers, then perhaps small leaf size is less important in choosing a particular species for use in bonsai culture. It cannot be said, then, that the range of species is a foundational, defining factor of bonsai; only that the subjective value judgements in design must first be identified, and the subsequent objective tools needed to achieve those goals must then be tested in species-specific contexts.

How about, then, the necessity of utilizing a single front view in bonsai design as a defining factor of the term? While this is certainly true in many cases, it is not a foundational element of bonsai. 

Bonsai often possess qualities that are visually appealing from a number of positions and that may be exploited to varying degrees in the evolution of each tree's design over its life. Bonsai necessarily change over time through natural and cumulative processes, and this invariably affects the chosen design of any given artist at any one point in time. Each time a bonsai is worked, subtle (or dramatic) changes occur, making whatever chosen front fleeting at best in the total life of a tree. While these snapshots in time represent the efforts and tastes of a given artist, they are sure to quickly fade. This is part of the dynamism and uniqueness of bonsai as art, to be embraced and experienced in the journey of each tree.

Where, then, does this leave us in our pursuit to objectively define bonsai? Thus far, the discussion has revolved around subtracting the elements that do not define the word. Here, let's attempt to parse out those that add to it.

First, let's discuss the medium with which we work in bonsai art - that is, living plant material. 

There are no exceptions to this fundamental component of bonsai. Yes, it is often the case that entire portions of individual plants are intentionally killed off for various design purposes, and yes, deadwood features are sometimes incorporated in multi-trunk and other compositions. But this in no way detracts from the core fact that bonsai necessarily requires living plant material to be considered as such. Otherwise, call it what it is - deadwood art or driftwood sculpture or a dead stick in a pot.

Next, by definition, this living plant material is at risk of no longer being alive, and thus to lose its status as a bonsai. It is then imperative upon us as creators, designers, and enthusiasts of bonsai art to hedge against this eventual inevitability by utilizing any number of scientifically based horticultural techniques to ensure and protect a given plant's longevity and status as a bonsai. By limiting the growth potential and root development of a plant, we are invariably weakening it over time. However, it is incumbent upon us to counter this decline by utilizing proper techniques, not only to prop up the health of the plant, but also to exploit (whether by inducing or limiting) growth habits conducive to attaining whatever subjective design goals we value. Identifying the objective techniques to be employed for reaching these subjective goals can, and must, be established through rigorous testing, preferably in a controlled environment.

Perhaps the most unique aspect of bonsai, and what sets it apart from other forms of art, is the element of time. While most works of art are static, created as snapshots in time to be viewed or experienced in perpetuity, in working with living plant material, bonsai is necessarily subject to change over time. 

Branches perish, foliage elongates, and the overall design shifts, sometimes subtly, sometimes dramatically. The variable of time is often overlooked in defining bonsai; however, it as perhaps the most important definitive aspect of the art. In creating, designing, or altering the appearance of a bonsai, we are doing so (or should be) with the explicit understanding that the decisions we make at any given point in time can and will manifest themselves in specific, predictable ways in the future - perhaps within a few days in a single growing season, or decades down the road. The foresight needed to make proper decisions in design is a skill that requires time and diligence to perfect, and it is an inseparable component from the proper practice of bonsai.

The definition of bonsai must also include an understanding of bonsai as an emergent art produced via the application of short-term and long-term maintenance and horticultural techniques. 

Not only are techniques for maintenance necessary to keep our chosen medium alive and thriving, but they are also part of the cumulative design process in bonsai art. I often find that the greatest common emphasis in this field is placed on the initial "bone-setting" aspect of design, and that this is what defines the artistry of bonsai. Certainly weight should be given to this area, but not at the expense, or to the diminishment, of the cumulative effects of proper maintenance on the design and form of a bonsai. This is a particularly potent argument in relation to deciduous species trained as bonsai, as the results of both good and bad maintenance techniques become glaringly obvious in the bare, winter months when the trees are free of foliage. How we deduce what techniques to apply to each species involves first identifying subjective design goals, followed by a rigorous, scientific examination of the objective horticultural practices necessary to achieve those outcomes.

The cumulative nature of bonsai art is further compounded by the very fact that many individual trees will pass through the hands of numerous artists throughout their existence as bonsai. Each subsequent person adds, whether subtly or dramatically, to the design of the plant, shifting angles, removing branches, changing species through grafting, etc. This process adds to the provenance of a bonsai and to the uniqueness of the art as a community practice. It should be noted that this communal effort can be, but is not always, collaborative. What is fascinating about bonsai in Japan is that the larger cultural context, which places great value on subtlety and nuance, has influenced the cumulative component of bonsai art. That is to say, while a single tree may pass through the hands of multiple professional artists, the stylistic differences between each artist are often only slightly perceptible, and it is in these subtleties that the beauty and depth of bonsai are found. It then becomes a fascinating cognitive exercise in attempting to identify the most recent artist of a given tree.

We have thus far established that our chosen medium must be living plant material planted in a container of one sort or another, it necessitates a time variable and will necessarily change over the length of this variable, and it requires design and maintenance components that are cumulative and communally influenced.  In summation, bonsai can be defined as "container-grown, living plant material, cumulatively and communally designed and maintained over time, to be viewed in snapshots that punctuate the material's total lifespan."

Perhaps it is not the shortest of definitions, but certainly one that encapsulates the complexities of the art of bonsai.

Check out additional info on what a bonsai is and pruning techniques at Porch.com!