Bonsai



 (盆栽 Japanese) (lit. tray cultivation) is the art of growing trees, or woody plants shaped as trees, in containers. Bonsai is sometimes confused with dwarfing, but dwarfing more accurately refers to researching and creating cultivars of plant material that are permanent, genetic miniatures of existing species. Bonsai does not require genetically dwarfed trees, but rather depends on growing small trees from regular stock and seeds. Bonsai uses cultivation techniques like pruning, root reduction, potting, defoliation, and grafting to produce small trees that mimic the shape and style of mature, full-sized trees.

The purposes of bonsai are primarily contemplation (for the viewer) and the pleasant exercise of effort and ingenuity (for the grower). By contrast with other plant cultivation practices, bonsai is not intended for production of food, for medicine, or for creating yard-sized or park-sized landscapes. Instead, bonsai practice focuses on long-term cultivation and shaping of one or more small trees in a single container.

'Bonsai' is a Japanese pronunciation of the earlier Chinese term penzai (盆栽). A 'bon' is a tray-like pot typically used in bonsai culture. The word bonsai is sometimes used as an umbrella term for all miniature trees in containers or pots, but this article focuses primarily on bonsai as defined in the Japanese tradition. Similar practices in other cultures include the Chinese tradition of penjing and the miniature living landscapes of Vietnamese hòn non bộ.

History
Container-grown plants, including trees and many other plant types, have a history stretching back at least to the early times of Egyptian culture. However, the lineage of bonsai derives directly from the Chinese penjing.

A concept and early versions
Imperial embassy personnel and Buddhist students from Japan had been returning from mainland China with many souvenirs, including occasional container planting, since the sixth century. At least 17 diplomatic missions were specifically sent from Japan to the Tang court between the years 603 and 839. From about the year 970 comes the first lengthy work of fiction in Japanese, Utsubo monogatari (The Tale of the Hollow Tree), which includes this passage: "A tree that is left growing in its natural state is a crude thing. It is only when it is kept close to human beings who fashion it with loving care that its shape and style acquire the ability to move one." The idea, therefore, was already established by this time that natural beauty becomes true beauty only when modified in accordance with a human ideal.

Saigyo Monogatari Emaki was the earliest known scroll to depict dwarfed potted trees in Japan. It dates from 1195, although some sources say this dates from 1250. From the year 1309, wooden tray and dish-like pots with dwarf landscapes on modern-looking wooden shelf/benches are shown in the Kasuga-gongen-genki scroll. These novelties show off the owner's wealth and were probably exotics imported from China.

With the extended invasion of the Mongol Empire into China, many artists and intellectuals found comfortable life and recognition in Japan where Song dynasty culture was still actively studied. Chinese Chan Buddhist monks came over to teach at monasteries, and one of the monks' activities was to introduce political leaders of the day to the various arts of miniature landscapes as ideal accomplishments for men of taste and learning.

The c.1300 rhymed prose essay, Bonseki no Fu (Tribute to Bonseki) written by celebrated priest and master of Chinese poetry, Kokan Shiren (1278–1346), outlined the aesthetic principles for what would be termed bonsai, bonseki and garden architecture itself. At first, the Japanese used miniaturized trees grown in containers to decorate their homes and gardens.

Criticism of the interest in curiously twisted specimens of potted plants shows up in one chapter of the 243 chapter compilation, Tsurezuregusa (c.1331). This work would become a sacred teaching handed down from master to student, through a limited chain of poets (some famous), until it was at last widely published in the early 17th century. Before then, the criticism had only a modest influence on dwarf potted tree culture.

In 1351, dwarf trees were displayed on short poles as portrayed in the Boki Ekotoba scroll. Several other scrolls and paintings also included depictions of these kinds of trees. Potted landscape arrangements made during the next hundred years or so included figurines after the Chinese fashion in order to add scale and theme. These miniatures would eventually be considered garnishes decidedly to be excluded by Japanese artists who were simplifying their creations in the spirit of Zen Buddhism.

Hachi-no-ki
Around the 14th century, the term for dwarf potted trees was "the bowl's tree" (鉢の木, hachi-no-ki ). This denoted the use of a fairly deep pot, as opposed to the shallow pot denoted by the term bonsai.

Hachi-No-Ki (The Potted Trees) is also the title of a Noh play by Zeami Motokiyo (1363–1444), based on a story from c.1383. It tells of an impoverished samurai who sacrifices his three last dwarf potted trees as firewood to provide warmth for a traveling monk on a winter night. The monk is an official in disguise who later rewards the samurai by giving him three lands whose names include the names of the three types of trees the samurai burnt: ume (plum), matsu (pine) and sakura (cherry). In later centuries, woodblock prints by several artists would depict this popular drama. There was even a fabric design of the same name.

Stories referring to bonsai began to appear more frequently by the 17th century. Shogun Tokugawa Iemitsu (r. 1623-1651) was a hachi-no-ki enthusiast. A story tells of Okubo Hikozemon (1560–1639), councilor to the shogun, who threw one of Iemitsu's favorite trees away in the garden — in sight of the shogun — in order to dissuade him from spending so much time and attention on these trees. In spite of the servant's efforts, Iemitsu never gave up his beloved art form. Another story from this time tells of a samurai's gardener who killed himself when his master insulted a hachi-no-ki of which the artisan was especially proud.

Bonsai dating to the 17th century have survived to the present. One of the oldest-known living bonsai trees, considered one of the National Treasures of Japan, is in the Tokyo Imperial Palace collection. A five-needle pine (Pinus pentaphylla var. negishi) known as Sandai-Shogun-No Matsu is documented as having been cared for by Tokugawa Iemitsu. The tree is considered to be at least 500 years old and was first trained as a bonsai by, at latest, the year 1610. The earliest known report by a Westerner of a Japanese dwarf potted tree was made in 1692 by George Meister.

Chinese bonsai containers exported to Japan during the 17th and 18th centuries would become referred to as Kowatari ('old crossing'). These were made between 1465 and about 1800. Many came from Yixing in Jiangsu province — unglazed and usually purplish-brown — and some others from around Canton, particularly during the Ming dynasty. Miniature potted trees were called hachi-ue in a 1681 horticulture book. This book also stated that everyone at the time grew azaleas, even if the poorest people had to use an abalone shell as a container. Torii Kiyoharu's use of woodblock printing in Japan depicted the dwarf potted trees from horticultural expert Itō Ihei's nursery.

By the end of the 18th century, bonsai cultivation was quite widespread and had begun to interest the public. In the Tenmei era (1781–88), an exhibit of traditional dwarf potted pines began to be held every year in Kyoto. Connoisseurs from five provinces and neighboring areas would bring one or two plants each to the show in order to submit them to visitors for ranking.

The classical bonsai period
In Itami, Hyogo (near Osaka), a group of scholars of Chinese arts gathered in the early nineteenth century to discuss recent styles in the art of miniature trees. Their version of these, which had been previously called "Bunjin Ueki," "Bunjin Hachiue," or other terms, were renamed "bonsai" (the Japanese pronunciation of the Chinese term penzai). This term had the connotation of a shallower container in which the Japanese could now more successfully style small trees. The term "bonsai," however, would not become regularly used in describing their dwarf potted trees for nearly a century. Many others terms and compositions adopted by this group were derived from Kai-shi-en Gaden, the Japanese version of Jieziyuan Huazhuan.

In 1829, a significant book that first established classical bonsai art, Somoku Kinyo Shu (A Colorful Collection of Trees and Plants/Collection of tree leaves), was published. It includes the basic criteria for the ideal form of the classical pine bonsai, in detail and with illustrations. That same year, small tako-tsuki (octopus-styled) trees with long, wavy-branches began to be offered by a grower in Asakusa Park, a north-eastern Edo suburb. Within 20 years that neighborhood became crowded with nurseries selling bonsai. The three-volume Kinsei-Jufu, possibly the first catalog of bonsai, tools, and pots, dates from 1833.

Numerous artists of the nineteenth century depicted dwarf potted trees in woodblock prints, including Yoshishige (who pictured each of the fifty-three classic stations of the Tokaido (road) as miniature landscape) and Kunisada (who included mostly hachi-no-ki in some four dozen prints). The earliest known photograph from Japan depicting a dwarf potted tree dates from c.1861 by Pierre Rossier.

On October 13, 1868, the Meiji Emperor moved to his new capital in Tokyo. Bonsai were displayed both inside and outside Meiji Palace, where they have since remained important in affairs of the Palace. Bonsai placed in the grand setting of the Imperial Palace had to be "Giant Bonsai," large enough to fill the grand space. The Meiji Emperor encouraged interest in bonsai. Government officials who did not appreciate bonsai fell out of favor. Soon all members of the ministry had bonsai whether they liked the tradition or not. Prince Itoh was an exception: any bonsai which the emperor gave him were then passed to Kijoji Itoh. Kijoji Itoh was a statesman of great influence behind the scenes, and a noted bonsai collector who conducted research and experiments on these bonsai.

Bonsai shaping aesthetics and techniques were becoming more sophisticated. By the late 1860s, thick combed and wetted hemp fibers were used to roughly shape the trunk and branches of miniature trees by pulling and tying them. The process was tedious and bothersome, and the final product was unsightly. Tips of branches would only be opened flat. Long, wavy-branched tako (octopus) style trees were mass-produced and designed in the [renamed capital] Tokyo for the increasing foreign tradewhile the more subtle and delicate bunjin-style trees designed in Kyoto and Osaka were for use in Japan. Tokyo preferred big trunks out of proportion and did not approve of Kyoto's finely-designed slender trunks. (This cultural rivalry would continue for a century.)

Pots exported from China between 1816 and 1911 (especially the late 1800s) were called Nakawatari (middle-crossing) or Chuwatari. Shallow rectangular or oval stoneware with carved feet and drainage holes, unglazed pots of this type were used at ancestral shrines and treasured by the Chinese. After the mid-century, certain Japanese antiquities dealers imported them and instant popular approval for this type of container for bonsai created a huge demand. Consequently, orders came from Japan to Yixing pottery centers specifically to make bonsai pots.

Through the later 19th century, Japanese participation in various international exhibitions introduced many in the U.S. and Europe to dwarf potted trees. Specimens from the displays went into Western hands following the closing of the fairs. Japanese immigrants to the U.S. West Coast and Hawaii Territory brought plants and cultivation experience with them. Export nurseries, most notably the Yokohama Gardeners Association, provided increasingly good quality dwarf potted trees for Americans and Europeans — even if the buyers did not have enough information or experience to actually keep the trees alive long-term.

An Artistic Bonsai Concours was held in Tokyo in 1892 followed by the publication of a three-volume commemorative picture book. This demonstrated a new tendency to see bonsai as an independent art form. In 1903, the Tokyo association Jurakukai held showings of bonsai and ikebana at two Japanese-style restaurants. Three years later, Bonsai Gaho (till c.1913), became possibly the first monthly magazine on the subject. By 1907, "on the outskirts of Tokio [dwarf] tree artists have formed a little colony of from twenty to thirty houses, and from this centre their work find its way to all parts of the world." "Its secrets are handed down from father to son in a few families, and are guarded with scrupulous care."

Count Okuma (1838–1922) maintained a famed collection of dwarf pines and dwarf plum trees.

In 1910, shaping with wire was described in the Sanyu-en Bonsai-Dan (History of Bonsai in the Sanyu nursery). Zinc-galvanized steel wire was initially used. Expensive copper wire was only used for trees which had real potential. Between 1911 and about 1940, mass-produced containers were exported from Yixing, China and made to the specifications of Japanese dealers. These were called Shinto (new crossing or arrival) or Shin-watare. These were made for increasing numbers of enthusiasts. Some containers, including primitive style ones, were also being made in Formosa. By 1914, "at the N.E. corner of Shiba Park is a permanent bazaar (the first of its kind established in Tokyo) where hosts of native-made gimcracks can be bought at fixed prices. The exhibits of potted plants and dwarf trees held here from time to time attract lovers of such things." Also this year, the first national annual bonsai show was held (through 1933) in Tokyo's Hibiya Park. During this period, the tokonoma in formal rooms and tea rooms became the main place for bonsai display. The shaped trees now shared space with other items such as scrolls, incense burners, Buddhist statues and tea ceremony implements.

The first issue of Bonsai magazine was published in 1921 by Norio Kobayashi (1889–1972). This influential periodical would run for 518 consecutive issues. Copper wire was being extensively used by this time. Major changes to a tree's shape could now be accomplished with wiring. Trees could be precisely and aesthetically wired, and then sold immediately. A greater number of both collected and nursery trees could now be trained for bonsai. The number of hobbyists increased due to the increased ability to style with wire, but there was also an increase in damaged or scarred trees.

The 1923 Great Kanto Earthquake and resulting fire devastated Tokyo, and gutted the downtown area where many bonsai were grown. And so two years later, a group of thirty families of downtown Tokyo professional growers established the Ōmiya Bonsai Village, northeast of the capital. The first great annual public exhibition of trees was held at the Asahi Newspaper Hall in Tokyo in 1927. The first of the very prestigious Kokufu-ten exhibitions were held in Tokyo's Ueno Park, beginning in 1934. By the following year, tokonoma display principles allowed for bonsai to be shown for the tree's individual beauty, not just for its spiritual or symbolic significance.

Toolsmith Masakuni I (1880–1950) helped design and produce the first steel tools specifically made for the developing requirements of bonsai styling.

By 1940, there were about 300 bonsai dealers in Tokyo, some 150 species of trees were being cultivated, and thousands of specimens annually were shipped to Europe and America. The first major book on the subject in English was published in the Japanese capital: Dwarf Trees (Bonsai) by Shinobu Nozaki (1895–1968). The first bonsai nurseries and clubs in the Americas were started by first and second-generation Japanese immigrants.

Caretaker of the Imperial bonsai collection, Kyuzo Murata (1902–1991), was one of very few persons allowed to take care of bonsai during the Pacific War. He gathered together and preserved many trees from the other Omiya growers and would water them under the protection of night. Throughout 1945, many old trees were the smallest casualties of the spring and summer napalm bombing of Tokyo (esp. March 9/10) and sixty-six other cities. Gardeners protected the Imperial collection trees from fire by pouring water over them after the Palace had been bombed on May 25/26. Following the surrender of Japan, there began the post-war re-evaluation and reviving of damaged collections of trees — including the Imperial - which would continue for over a decade as Japan was rebuilt. Many of the Omiya growers did not continue their vocation. During the Allied Occupation of Japan (through 1952) U.S. officers and their wives could take courses in bonsai, bonkei, ikebana, and other traditional arts and crafts as arranged by General MacArthur's headquarters. Many of the older and limited varieties of trees were no longer available, and the bonsai considered in fashion changed partly because of this shortage. Copper wire now largely replaced ordinary iron wire for shaping the better trees, but the latter still would be used for mass-produced commercial bonsai.

The rise of modern bonsai
Following World War II, a number of trends made the Japanese tradition of bonsai more and more accessible to Western and world audiences. One key trend was the increase in the number, scope, and prominence of bonsai exhibitions. For example, the Kokufu-ten bonsai displays reappeared in 1947 after a four-year cancellation and became annual affairs. The displays are by invitation only for eight days in February, and continue to this day. In October 1964, a great exhibition was held by the private Kokufu Bonsai Association, reorganized into the Nippon Bonsai Association, in Hibya Park to mark the Tokyo Olympics. A commemorative album Gems of Bonsai and Suiseki was published in Japanese and English.

Another key trend was the increase in books on bonsai and related arts, now being published in English and other languages for audiences outside Japan. In 1952, Yuji Yoshimura, son of a leader in the Japanese bonsai community, collaborated with German diplomat and author Alfred Koehn to give demonstrations and the first formal bonsai courses opened to the public and outsiders in Tokyo. Koehn had been an enthusiast before the war, and his 1937 book Japanese Tray Landscapes had been published in English in Peking. Yoshimura's 1957 book The Art of Bonsai, written in English with his student Giovanna M. Halford, addressed both cultivation and aesthetic aspects of bonsai growing and went on to be called the “classic Japanese bonsai bible for westerners” with over thirty printings. The related art of saikei was presented to English-speaking audiences in 1963 in Kawamoto and Kurihara's Bonsai-Saikei. This book described tray landscapes made with younger material than was traditionally used in bonsai, providing an alternative to the use of large, older plants, few of which had escaped war damage.

Other works in Japanese and English had been published by this time, and afterward a tremendous number of books saw print. Translations and original volumes in over two dozen languages were published in the next few decades. The number of clubs outside of Asia increased once Japanese was no longer the sole language of bonsai, and interaction increased between members of all levels of experience.

A third trend was the increasing availability of expert bonsai training, at first only in Japan and then more widely. In 1967 the first group of Westerners studied at an Ōmiya nursery. Returning to the U.S. these people established the American Bonsai Society. Other groups and individuals from outside Asia then visited and studied at the various Japanese nurseries, occasionally even apprenticing under the masters. These visitors brought back to their local clubs the latest techniques and styles, which were then further disseminated. Japanese teachers also traveled widely, bringing hands-on bonsai expertise to every continent except Antarctica.

By the beginning of the 1970s, these trends were beginning to merge. A large display of bonsai and suiseki was held as part of Expo '70, and formal discussion was made of an international association of enthusiasts. Three monthly magazines were started this year: Bonsai Sekai, Satsuki Kenkyu, and Shizen to Bonsai. In 1975, first Gafu-ten (Elegant-Style Exhibit) of shohin bonsai (13-25 cm (5–10 in) tall) was held. So was the first Sakufu-ten (Creative Bonsai Exhibit), the only event in which professional bonsai growers exhibit traditional trees under their own names rather than under the name of the owner. It was organized by Hideo Kato (1918–2001) at Daimaru Department Store in Tokyo.

The First World Bonsai Convention was held in Osaka during the World Bonsai and Suiseki Exhibition in 1980. Nine years later, the first World Bonsai Convention was held in Omiya and the World Bonsai Friendship Federation (WBFF) was inaugurated. These conventions attracted several hundreds of participants from dozens of countries and have since been held every four years at different locations around the globe: 1993, Orlando, Florida; 1997, Seoul, Korea; 2001, Munich, Germany; 2005, Washington, D.C.; 2009, San Juan, Puerto Rico.

The final trend supporting world involvement in bonsai is the widening availability of specialized bonsai plant stock, soil components, tools, pots, and other accessory items. Bonsai nurseries in Japan advertise and ship specimen bonsai world-wide. Most countries have local nurseries providing plant stock as well, although finding specimen bonsai is more difficult outside Japan and bonsai enthusiasts will often start with local trees that have not been pre-shaped into candidate bonsai. Japanese bonsai soil components, such as Akadama clay, are available worldwide, and local suppliers also provide similar materials in many locations. Specialized bonsai tools are widely available from Japanese and Chinese sources. Finally, potters around the globe provide material to hobbyists and specialists in many countries.

Bonsai has now definitively reached a world-wide audience. There are over twelve hundred books on bonsai and the related arts in at least twenty-six languages available in over ninety countries and territories. A few dozen magazines in over thirteen languages are in print. Several score of club newsletters are available on-line, and there are at least that many discussion forums and blogs. Educational videos and just the appearance of dwarf potted trees in films and on television reach a wide audience. There are perhaps hundreds of thousands of enthusiasts in over a thousand clubs and associations worldwide, as well as an unknown number of unassociated hobbyists. Plant material from every location is being trained into bonsai and displayed at local, regional, national, and international conventions and exhibitions for enthusiasts and the general public.

Cultivation
Bonsai can be created from nearly any perennial woody-stemmed tree or shrub species which produces true branches and remains small through pot confinement with crown and root pruning. Some species are popular as bonsai material because they have characteristics, such as small leaves or needles, that make them appropriate for the compact visual scope of bonsai.

Sources of bonsai material
All bonsai start with a specimen of source material, a plant that the grower wishes to train into bonsai form. Bonsai practice is an unusual form of plant cultivation in that growth from seeds is rarely used to obtain source material. To display the characteristic aged appearance of a bonsai within a reasonable time, the source plant is often partially-grown or mature stock. A specimen may be selected specifically for bonsai aesthetic characteristics it already possesses, such as great natural age for a specimen collected in the wild, or a tapered, scar-free trunk from a nursery specimen. Alternatively, it may be selected for non-aesthetic reasons, such as known hardiness for the grower's local climate or low cost (in the case of collected materials).

Propagation
While any form of plant propagation could generate bonsai material, a few techniques are favored because they can quickly produce a relatively mature trunk with well-placed branches.

Cuttings. In taking a cutting, part of a growing plant is cut off and placed in a growing medium to develop roots. If the part that is cut off is fairly thick, like a mature branch, it can be grown into an aged-looking bonsai more quickly than can a seed. Unfortunately, thinner and younger cuttings tend to strike roots more easily than thicker or more mature ones. In bonsai propagation, cuttings usually provide source material to be grown for some time before training.

Layering. Layering is a technique in which rooting is encouraged from part of a plant, usually a branch, while it is still attached to the parent plant. After rooting, the branch is removed from the parent and grown as an independent entity. For bonsai, both ground layering and air layering can create a potential bonsai, by transforming a mature branch into the trunk of a new tree. The point at which rooting is encouraged can be close to the location of side branches, so the resulting rooted tree can immediately have a thick trunk and low branches, characteristics that complement bonsai aesthetics.

Commercial bonsai growers
Commercial bonsai growers may use any of the other means of obtaining starter bonsai material, from seed propagation to collecting expeditions, but they generally sell mature specimens that display bonsai aesthetic qualities already. The grower trains the source specimens to a greater or lesser extent before sale, and the trees may be ready for display as soon as they are bought. Those who purchase commercially-grown bonsai face some challenges, however, particularly of buying from another country. If the purchaser's local climate does not closely match the climate in which the bonsai was created, the plant will have difficulties surviving and thriving. As well, importing living plant material from a foreign source is often closely controlled by import regulations and may require a license or other special import arrangement on the buyer's part. If a local commercial bonsai grower does not exist, buying from a distant one may be unsatisfactory.

Nursery stock
A plant nursery is an agricultural operation where (non-bonsai) plants are propagated and grown to usable size. Nursery stock may be available directly from the nursery, or may be sold in a garden centre or similar resale establishment. Nursery stock is usually young but fully viable, and is often potted with sufficient soil to allow plants to survive a season or two before being transplanted into a more permanent location. Because the nursery tree is already pot-conditioned, it can be worked on as a bonsai immediately. The large number of plants that can be viewed in a single visit to a nursery or garden centre allows the buyer to identify plants with better-than-average bonsai characteristics. According to Peter Adams, a nursery visit "offers the opportunity to choose an instant trunk". One issue with nursery stock is that many specimens are shaped into popular forms, such as the standard or half-standard forms, with several feet of clear trunk rising from the roots. Without branches low on the trunk, it is difficult for a source specimen to be trained as bonsai.

Collecting
Collecting bonsai is the process of finding suitable bonsai material in its original wild situation, successfully moving it, and replanting it in a container for development as bonsai. Collecting may involve wild materials collected from naturally treed areas, or cultivated specimens found growing in yards and gardens. Mature landscape plants which are being discarded from a building site can provide excellent material for bonsai. In Great Britain, hedgerow trees that have grown for many years but have been continually trimmed down to hedge height provide heavy, gnarled trunks for bonsai growers.

Some regions have plant material that is known for its suitability in form. In North America, for example, the California Juniper and Sierra Juniper found in the Sierra Mountains, the Ponderosa pine and Rocky Mountain Juniper found in the Rocky Mountains, and the Bald Cypress found in the swamps of the Everglades. In Western North America species that are collected include; Rocky Mountain Juniper, Sub-Alpine Fir, Common Juniper, Ponderosa Pine, Lodgepole Pine,Mt. Hemlock, Western Hemlock and some Cedars.

The benefit of collecting bonsai specimens is that the collected materials can be mature, and will display the natural marks and forms of age, which makes them more suitable for bonsai development than the young plants obtained through nurseries. Some of the difficulties of collecting include getting permission to remove the specimens, and the challenges of keeping a mature tree alive while transplanting it to a bonsai pot.

Techniques
The practice of bonsai development incorporates a number of techniques either unique to bonsai or, if used in other forms of cultivation, applied in unusual ways that are particularly suitable to the bonsai domain.

Leaf trimming
This technique involves the selective removal of leaves (for most varieties of deciduous tree) or needles (for coniferous trees and some others) from a bonsai's trunk and branches. A common aesthetic technique in bonsai design is to expose the tree's branches below groups of leaves or needles (sometimes called "pads"). In many species, particularly coniferous ones, this means that leaves or needles projecting below their branches must be trimmed off. For some coniferous varieties, such as spruce, branches carry needles from the trunk to the tip and many of these needles may be trimmed to expose the branch shape and bark. Needle and bud trimming can also be used in coniferous trees to force back-budding or budding on old wood, which may not occur naturally in many conifers. Along with pruning, leaf trimming is the most common activity used for bonsai development and maintenance, and the one that occurs most frequently during the year.

Pruning
The small size of the tree and some dwarfing of foliage result from pruning the trunk, branches, and roots. Pruning is often the first step in transforming a collected plant specimen into a candidate for bonsai. The top part of the trunk may be removed to make the tree more compact. Major and minor branches that conflict with the designer's plan will be removed completely, and others may be shortened to fit within the planned design. Pruning later in the bonsai's life is generally less severe, and may be done for purposes like increasing branch ramification or encouraging growth in non-pruned branches. Although pruning is an important and common bonsai practice, it must be done with care, as improper pruning can weaken or kill trees. Careful pruning throughout the tree's life is necessary, however, to maintain a bonsai's basic design, which can otherwise disappear behind the uncontrolled natural growth of branches and leaves.

Wiring
Wrapping copper or aluminium wire around branches and trunks allows the bonsai designer to create the desired general form and make detailed branch and leaf placements. When wire is used on new branches or shoots, it holds the branches in place until they lignify (convert into wood). The time required is usually 6–9 months or one growing season for deciduous, but can be several years for conifers like pines and spruce, which maintain their branch flexibility through multiple growing seasons. Wires are also used to connect a branch to another object (e.g., another branch, the pot itself) so that tightening the wire applies force to the branch. Some species do not lignify strongly, and some specimens' branches are too stiff or brittle to be bent easily. These cases are not conducive to wiring, and shaping them is accomplished primarily through pruning.

Clamping
For larger specimens, or species with stiffer wood, bonsai artists also use mechanical devices for shaping trunks and branches. The most common are screw-based clamps, which can straighten or bend a part of the bonsai using much greater force than wiring can supply. To prevent damage to the tree, the clamps are tightened a little at a time and make their changes over a period of months or years.

Grafting
In this technique, new growing material (typically a bud, branch, or root) is introduced to a prepared area on the trunk or under the bark of the tree. There are two major purposes for grafting in bonsai. First, a number of favorite species do not thrive as bonsai on their natural root stock and their trunks are often grafted onto hardier root stock. Examples include Japanese red maple and Japanese black pine. Second, grafting allows the bonsai artist to add branches (and sometimes roots) where they are needed to improve or complete a bonsai design. There are many applicable grafting techniques, none unique to bonsai, including branch grafting, bud grafting, thread grafting, and others.

Defoliation
Short-term dwarfing of foliage can be accomplished in certain deciduous bonsai by partial or total defoliation of the plant partway through the growing season. Not all species can survive this technique. In defoliating a healthy tree of a suitable species, most or all of the leaves are removed by clipping partway along each leaf's petiole (the thin stem that connects a leaf to its branch). Petioles later dry up and drop off or are manually removed once dry. The tree responds by producing a fresh crop of leaves. The new leaves are generally much smaller than those from the first crop, sometimes as small as half the length and width. If the bonsai is shown at this time, the smaller leaves contribute greatly to the bonsai esthetic of dwarfing. This change in leaf size is usually not permanent, and the leaves of the following spring will often be the normal size. Defoliation weakens the tree and should not be performed in two consecutive years.

Deadwood
Bonsai growers use deadwood bonsai techniques called jin and shari to simulate age and maturity in a bonsai. Jin is the term used when the bark from an entire branch is removed to create the impression of a snag of deadwood. Shari denotes stripping bark from areas of the trunk to simulate natural scarring from a broken limb or lightning strike. In addition to stripping bark, this technique may also involve the use of tools to scar the deadwood or to raise its grain, and the application of chemicals (usually lime sulfur) to bleach and preserve the exposed deadwood.

Watering
With limited space in a bonsai pot, regular attention is needed to ensure the tree is correctly watered. Sun, heat and wind exposure can dry bonsai trees to the point of drought in a short period of time. While some species can handle periods of relative dryness, others require near-constant moisture. Watering too frequently, or allowing the soil to remain soggy, promotes fungal infections and root rot. Free draining soil is used to prevent waterlogging. Deciduous trees are more at risk of dehydration and will wilt as the soil dries out. Evergreen trees, which tend to cope with dry conditions better, do not display signs of the problem until after damage has occurred.

Repotting


Bonsai are repotted and root-pruned at intervals dictated by the vigour and age of each tree. In the case of deciduous trees, this is done as the tree is leaving its dormant period, generally around springtime. Bonsai are often repotted while in development, and less often as they become more mature. This prevents them from becoming pot-bound and encourages the growth of new feeder roots, allowing the tree to absorb moisture more efficiently.

Specimens meant to be developed into bonsai are often placed in "growing boxes", which have a much larger volume of soil per plant than a bonsai pot does. These large boxes allow the roots to grow freely, increasing the vigor of the tree and helping the trunk and branches grow thicker. After using a grow box, the tree may be replanted in a more compact "training box" that helps to create a smaller, denser root mass which can be more easily moved into a final presentation pot.

Tools


Special tools are available for the maintenance of bonsai. The most common tool is the concave cutter (5th from left in picture), a tool designed to prune flush, without leaving a stub. Other tools include branch bending jacks, wire pliers and shears of different proportions for performing detail and rough shaping.

Soil and fertilization


Bonsai soil is usually a loose, fast-draining mix of components, often a base mixture of coarse sand or gravel, fired clay pellets, or expanded shale combined with an organic component such as peat or bark. The inorganic components provide mechanical support for bonsai roots, and—in the case of fired clay materials—also serve to retain moisture. The organic components retain moisture and may release small amounts of nutrients as they decay.

In Japan, bonsai soil mixes based on volcanic clays are common. The volcanic clay has been fired at some point in time to create porous, water-retaining pellets. Varieties such as akadama, or "red ball" soil, and kanuma, a type of yellow pumice used for azaleas and other calcifuges, are used by many bonsai growers. Similar fired clay soil components are extracted or manufactured in other countries around the world, and other soil components like diatomaceous earth can fill a similar purpose in bonsai cultivation.

Opinions about fertilizers and fertilization techniques vary widely among practitioners. Some promote the use of organic fertilizers to augment an essentially inorganic soil mix, while others will use chemical fertilizers freely. Many follow the general rule of little and often, where a dilute fertilizer solution or a small amount of dry fertilizer are applied relatively frequently during the tree's growing season. The flushing effect of regular watering moves unmetabolized fertilizer out of the soil, preventing the potentially toxic build-up of fertilizer ingredients.

Location and overwintering
Bonsai are sometimes marketed or promoted as house plants, but few of the traditional bonsai species can thrive or even survive inside a typical house. The best guideline to identifying a suitable location for a bonsai is its native hardiness. If the bonsai grower can closely replicate the full year's temperatures, relative humidity, and sunlight, the bonsai should do well. In practice, this means that trees from a hardiness zone closely matching the grower's location will generally be the easiest to grow outdoors, and others will require more work or will not be viable at all.

Outdoors
Most bonsai species are outdoor trees and shrubs by nature, and they require temperature, humidity, and sunlight conditions approximating their native climate year round. The skill of the gardener can help plants from outside the local hardiness zone to survive and even thrive, but doing so takes careful watering, shielding of selected bonsai from excessive sunlight or wind, and possibly protection from winter conditions (e.g., through the use of cold boxes or winter greenhouses).

Common bonsai species (particularly those from the Japanese tradition) are temperate climate trees from hardiness zones 7 to 9, and require moderate temperatures, moderate humidity, and full sun in summer with a dormancy period in winter that may need be near freezing. They do not thrive indoors, where the light is generally too dim, and humidity often too low, for them to grow properly. Only in the dormant period can they safely be brought indoors, and even then the plants require cold temperatures, reduced watering, and lighting that approximates the number of hours the sun is visible. Raising the temperature or providing more hours of light than available from natural daylight can cause the bonsai to break dormancy, which often weakens or kills it.

Indoors
Tropical and Mediterranean species typically require consistent temperatures close to room temperature, and with correct lighting and humidity many species can be kept indoors all year. Those from cooler climates may benefit from a winter dormancy period, but temperatures need not be dropped as far as for the temperate climate plants and a north-facing windowsill or open window may provide the right conditions for a few winter months.

Aesthetics
Bonsai aesthetics are the aesthetic goals and characteristics of the Japanese tradition in the art of growing a miniature tree in a container. Many Japanese cultural characteristics, particularly the influence of Zen Buddhism and the expression of wabi or sabi, inform the bonsai tradition in Japan. A number of other cultures around the globe have adopted the Japanese approach to bonsai, and while some variations have begun to appear, most hew closely to the rules and design philosophies of the Japanese tradition. Related arts that share some aesthetic principles with bonsai include penjing and saikei.

Over centuries of practice, the Japanese bonsai aesthetic has encoded some important methods and aesthetic guidelines. Like the type of aesthetic rules that govern, for example, Western common practice period music, bonsai's guidelines help practitioners work within an established tradition with some assurance of success. Guidelines alone do not guarantee a successful result. Nevertheless, these design rules can rarely be broken without reducing the impact of the bonsai specimen. Some of the key principles in bonsai aesthetics include:


 * Miniaturization. By definition, a bonsai is a tree which is kept small enough to be container-grown while otherwise fostered to have a mature appearance.


 * Proportion among elements. The most prized proportions mimic those of a full-grown tree as closely as possible. Small branches with large leaves or needles are out of proportion and are avoided, as is a thin trunk with thick branches.


 * Asymmetry. Bonsai aesthetics discourage strict radial or bilateral symmetry in branch and root placement


 * No trace of the artist. The designer's touch must not be apparent to the viewer. If a branch is removed in shaping the tree, the scar will be concealed. Similarly, wiring must leave no permanent marks on the branch or bark.


 * Gravitas. Many of the formal rules of bonsai help the grower create a tree that expresses wabi or sabi, or portrays an aspect of mono no aware.

Display
A bonsai display presents one or more bonsai specimens in a way that allows a viewer to see all the important features of the bonsai from the most advantageous position. That position emphasizes the bonsai's defined "front", which is designed into all bonsai. It places the bonsai at a height that allows the viewer to imagine the bonsai as a full-sized tree seen from a distance, siting the bonsai neither so low that the viewer appears to be hovering in the sky above it, nor so high that the viewer appears to be looking up at the tree from beneath the ground. Peter Adams recommends that bonsai be shown as if "in an art gallery: at the right height; in isolation; against a plain background, devoid of all redundancies such as labels and vulgar little accessories."

For outdoor displays, there are few aesthetic rules. Many outdoor displays are semi-permanent, with the bonsai trees in place for weeks or months at a time. To avoid damaging the trees, therefore, an outdoor display must not impede the amount of sunlight needed for the trees on display, must support watering, and may also have to block excessive wind or precipitation. As a result of these practical constraints, outdoor displays are often rustic in style, with simple wood or stone components. A common design is the bench, sometimes with sections at different heights to suit different sizes of bonsai, along which bonsai are placed in a line. Where space allows, outdoor bonsai specimens are spaced far enough apart that the viewer can concentrate on one at a time. When the trees are too close to each other, aesthetic discord between adjacent trees of different sizes or styles can confuse the viewer, a problem addressed by exhibition displays.

Exhibition displays allow a large number of bonsai to be displayed in a temporary exhibition format, typically indoors, as would be seen in a bonsai design competition. To allow many trees to be located close together, exhibition displays often use a sequence of small alcoves, each containing one pot and its bonsai contents. The walls or dividers between the alcoves make it easier to view only one bonsai at a time. The back of the alcove is a neutral color and pattern to avoid distracting the viewer's eye. The bonsai pot is almost always placed on a formal stand, of a size and design selected to complement the bonsai and its pot.

Indoors, a formal bonsai display is arranged to represent a landscape, and traditionally consists of the featured bonsai tree in an appropriate pot atop a wooden stand, along with a shitakusa (companion plant) representing the foreground, and a hanging scroll representing the background. These three elements are chosen to complement each other and evoke a particular season, and are composed asymmetrically to mimic nature. When displayed inside a traditional Japanese home, a formal bonsai display will often be placed within the home's tokonoma or formal display alcove. An indoor display is usually very temporary, lasting a day or two, as most bonsai are intolerant of indoor conditions and lose vigor rapidly within the house.

Containers
A variety of informal containers may house the bonsai during its development, and even trees that have been formally planted in a bonsai pot may be returned to growing boxes from time to time. A large growing box will house several bonsai and provide a great volume of soil per tree to encourage root growth. A training box will have a single tree, and a smaller volume of soil that helps condition the tree to the eventual size and shape of the formal bonsai container. There are no aesthetic guidelines for these development containers, and they may be of any material, size, and shape that suit the grower.

Formal bonsai containers are ceramic pots, which come in a variety of shapes and colors and may be glazed or unglazed. Unlike many common plant containers, bonsai pots have drainage holes in the bottom surface to allow excess water to escape the pot. The grower usually covers the holes with a piece of screen or mesh to prevent soil from falling out and hinder pests from entering the pots from below.

For bonsai being shown in their completed state, pot shape, color, and size are chosen to complement the tree as a picture frame is chosen to complement a painting. Containers with straight sides and sharp corners are generally used for formally-shaped plants, while oval or round containers are used for plants with informal designs. Many aesthetic rules guide the selection of pot finish and color. For example, evergreen bonsai are often placed in unglazed pots, while deciduous trees usually appear in glazed pots. Pots are also distinguished by their size. The overall design of the bonsai tree, the thickness of its trunk, and its height are considered when determining the size of a suitable pot.

Some pots are highly collectible, like ancient Chinese or Japanese pots made in regions with experienced pot makers such as Tokoname, Japan or Yixing, China. Today many western potters throughout Europe and North America produce fine quality pots for bonsai.

Common styles


The most common styles include formal upright, informal upright, slanting, semi-cascade, cascade, raft, literati, and group/forest. Less common forms include windswept, weeping, split-trunk, and driftwood styles.


 * The formal upright style, or Chokkan, is characterized by a straight, upright, tapering trunk. Branches progress regularly from the thickest and broadest at the bottom to the finest and shortest at the top.


 * The trunk and branches of the informal upright style, or Moyogi incorporate visible curves, but the apex of the informal upright is always located directly above the trunk's entry into the soil line. Similar to the formal upright style, branches generally progress regularly from largest at the bottom to smallest at the top, although this progression may be broken where the irregular shape of the trunk would make a branch abnormally prominent or obscure.


 * Slant-style, or Shakan, bonsai possess straight trunks like those of bonsai grown in the formal upright style. However, the slant style trunk emerges from the soil at an angle, and the apex of the bonsai will be located to the left or right of the root base.


 * Cascade-style, or Kengai, bonsai are modeled after trees which grow over water or on the sides of mountains. The apex, or tip of the tree in the Semi-cascade-style, or Han Kengai, bonsai extend just at or beneath the lip of the bonsai pot; the apex of a (full) cascade style falls below the base of the pot.


 * Raft-style, or Netsuranari, bonsai mimic a natural phenomenon that occurs when a tree topples onto its side, for example, from erosion or another natural force. Branches along the top side of the trunk continue to grow as a group of new trunks. Sometimes, roots will develop from buried portions of the trunk. Raft-style bonsai can have sinuous, straight-line, or slanting trunks, all giving the illusion that they are a group of separate trees—while actually being the branches of a tree planted on its side.


 * The literati style, or Bunjin-gi, bonsai is characterized by a generally bare trunk line, with branches reduced to a minimum, and typically placed the top of a long, often contorted trunk. This style derives its name from the Chinese literati who created Chinese brush paintings like those found in the ancient text, The Mustard Seed Garden Manual of Painting. Their minimalist landscapes often depicted trees growing in harsh conditions, with contorted trunks and reduced foliage. In Japan, the literati style is known as bunjin-gi (文人木). (Bunjin is a translation of the Chinese phrase wenren meaning "scholars practiced in the arts" and gi is a derivative of the Japanese word, ki, for "tree").


 * The group or forest style, or Yose Ue, comprises a planting of several or many trees, and typically an odd number, in a bonsai pot. The trees are usually the same species, with a variety of heights employed to add visual interest and to reflect the age differences encountered in mature forests.


 * The broom style, or Hokidachi, is employed for trees with extensive, fine branching, often with species like elms. The trunk is straight and upright. It branches out in all directions about 1/3 of the way up the entire height of the tree. The branches and leaves form a ball-shaped crown which can also be very beautiful during the winter months.


 * The multi-trunk style, or Ikadabuki, has all the trunks growing out of one spot with one root system, and it actually is one single tree. Its counterpart in nature is the tree clump formed, for example, where a single pine cone has sprouted a number of seedlings in one spot. All the trunks combine to support one crown of leaves, in which the thickest and most developed trunk forms the top.
 * The Shari style, or Sharimiki, style involves portraying a tree in its struggle to live while a significant part of its trunk is bare of bark. In nature, trees in the Sharimiki style are created by lightning or animals eating the bark.


 * The root-over-rock style, or Sekijoju, is a style in which the roots of the tree are wrapped around a rock. The rock is at the base of the trunk, with the roots exposed to varying degrees as they traverse the rock and then descend into the soil below.


 * The growing-in-a-rock, or Ishizuke, style means the roots of the tree are growing in soil contained within the cracks and holes of the rock. The rock may serve as a simple container, with the tree escaping the container and forming its own shape. Alternatively, the tree may show a definite relationship to the rock's shape, growing close to the rock and following its contours.

Size classifications
Not all sources agree on the exact sizes or names for these ranges, but the concept of the ranges is well-established and necessary to both the cultivation and the aesthetic understanding of the trees. In the very largest size range, a recognized Japanese practice is to name the trees "one-handed", "two-handed", and so on, based on the number of men required to move the tree and pot. These trees will have dozens of branches and can closely simulate a full-sized tree. At the other end of the size spectrum, there are a number of specific techniques and styles associated solely with the smallest sizes, mame and shito. These techniques take advantage of the bonsai's minute dimensions and compensate for the limited number of branches and leaves that can appear on a tree this small.