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 gardens or landscapes. Instead, bonsai practice focuses on long-term cultivation and shaping of one or more small trees in a single container .
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
Cultivation and care
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. Bonsai cultivation and care requires techniques and tools that are specialized to support the growth and long-term maintenance of trees in small containers.
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. Sources of bonsai material include:
Propagation through cuttings or layering.
Commercial bonsai growers, which generally sell mature specimens that display bonsai aesthetic qualities already.
Nursery stock directly from a nursery, or from a garden centre or similar resale establishment.
Collecting suitable bonsai material in its original wild situation, successfully moving it, and replanting it in a container for development as bonsai.
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. These techniques include:
Leaf trimming, 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.
Pruning the trunk, branches, and roots of the candidate tree.
Wiring branches and trunks allows the bonsai designer to create the desired general form and make detailed branch and leaf placements.
Clamping using mechanical devices for shaping trunks and branches.
Grafting new growing material (typically a bud, branch, or root) into a prepared area on the trunk or under the bark of the tree.
Defoliation, which can provide short-term dwarfing of foliage for certain deciduous species.
Deadwood bonsai techniques called jin and shari simulate age and maturity in a bonsai.
Small trees grown in containers, like bonsai, require specialized care. Unlike houseplants and other subjects of container gardening, tree species in the wild generally grow roots up to several meters long and root structures encompassing several thousand liters of soil. In contrast, a typical bonsai container is under 25 centimeters in its largest dimension and 2 to 10 liters in volume. Branch and leaf (or needle) growth in trees is also large-scale in nature. Wild trees typically grow 5 meters or taller when mature, while the largest bonsai rarely exceed 1 meter and most specimens are significantly smaller. These size differences affect maturation, transpiration, nutrition, pest resistance, and many other aspects of tree biology. Maintaining the long-term health of a tree in a container requires some specialized care techniques:
Watering must be regular and must relate to the bonsai species' requirement for dry, moist, or wet soil.
Repotting must occur at intervals dictated by the vigour and age of each tree.
Tools have been developed for the specialized requirements of maintaining bonsai.
Soil composition and fertilization must be specialized to the needs of each bonsai tree, although bonsai soil is almost always a loose, fast-draining mix of components.
Location and overwintering are also species-dependent, and it is important to note that few of the traditional bonsai species can thrive or even survive inside a typical house.
Bonsai aesthetics are the aesthetic goals characterizing the Japanese tradition of growing an artistically-shaped 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. Established art forms that share some aesthetic principles with bonsai include penjing and saikei. 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.
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 trees 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.
Poignancy. 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.
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.
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.
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 . (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.
Indoor bonsai are bonsai which are cultivated for the indoor environment. Traditionally, bonsai are temperate climate trees grown outdoors in containers. Kept in the artificial environment of a home, these trees weaken and die. But a number of tropical and sub-tropical tree species will survive and grow indoors. Some of these are suited to bonsai aesthetics and can be shaped much as traditional outdoor bonsai are.