Bonsai (literally "potted plant") is the art of aesthetic miniaturization of trees by growing them in containers. Cultivation includes techniques for shaping, watering, and repotting in various styles of containers.
Originating in China during the Han Dynasty, 'bonsai' is a Japanese pronunciation of the Chinese word penzai. The word bonsai is used in the West as an umbrella term for all miniature trees in containers or pots.
The origins of bonsai are believed to have begun at least 2000 years ago during the Han Dynasty in China. It has since developed into new forms in parts of China, Japan, Korea and Vietnam.
At first, the Japanese used miniaturized trees grown in containers to decorate their homes and gardens. During the Tokugawa period, landscape gardening attained new importance. Cultivation of plants such as azalea and maples became a pastime of the wealthy. Growing dwarf plants in containers was also popular. At this time, the term for dwarf potted trees was "a tree in a pot".
The c.1300 rhymed prose essay, Rhymeprose on a Miniature Landscape Garden, by the Japanese Zen monk Kokan Shiren, outlines the aesthetic principles for bonsai, bonseki and garden architecture itself.
The oldest known living bonsai trees are in the collection at Happo-en (a private garden and exclusive restaurant) in Tokyo, Japan, where bonsai are between 400 to 800 years old.
Bonsai are not genetically dwarfed plants. They can be created from nearly any tree or shrub species and remain small through pot confinement with crown and root pruning. Some specific species are more sought after for use as bonsai material, because they have characteristics that make them appropriate for the smaller design arrangements of bonsai.
The small size of the tree and the dwarfing of foliage result from pruning of both the leaves and the roots. Most trees require a dormancy period and do not grow roots or leaves at that time. Improper pruning can weaken or kill trees.
Copper or aluminium wire wrapped around branches and trunks holds the branches in place until they lignify (convert into wood), usually 6-9 months or one growing season. Some species do not lignify strongly, or are already too stiff/brittle to be shaped and are not conducive to wiring, in which case shaping is accomplished primarily through pruning.
Cultivators 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.
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.
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.
Pre-bonsai material are often placed in "growing boxes" which are made from scraps of fenceboard or wood slats. These large boxes allow the roots to grow more freely and increase the vigor of the tree. The second stage, after using a grow box, has been to replant the tree in a "training box;" this is often smaller and helps to create a smaller dense root mass which can be more easily moved into a final presentation pot.
Most bonsai are trained using malleable wire made from copper or copper colored aluminium. This is wrapped around the developing branches and trunk, allowing them to be moved into the desired shape and held in place by the wire. The tree is wired for at least one growing season to allow the branches to set in their new position. Some trees do not respond well to wiring and are shaped instead by pruning.
Soil and fertilization
Opinions about soil mixes and fertilization 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. Bonsai soil is primarily 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. In Japan, volcanic soils based on clay are preferred, such as akadama, or "red ball" soil, and kanuma, a type of yellow pumice used for azaleas and other calcifuges.
Location and overwintering
Most traditional bonsai are temperate climate trees and are kept outside all year. They require full sun in summer and usually a near-freezing dormancy period in winter. Depending on how hardy the tree species is, protection from very low temperatures may be required. Certain tropical species can survive winter without a dormancy period, and can therefore be kept indoors all year.
Bonsai pots have drainage holes typically covered with a plastic screen or mesh to prevent soil from escaping.
Containers come in a variety of shapes and colors and can be glazed or unglazed. Containers with straight sides and sharp corners are generally better suited to formally presented plants, while oval or round containers might be used for plants with informal shapes. Most evergreen bonsai are placed in unglazed pots, while deciduous trees are planted in glazed pots. It is important in design that the color of the pot compliments the tree. Some pots are highly collectible, such as 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 the United States produce fine quality pots for Bonsai.
In English, the most common styles include: formal upright, slant, informal upright, cascade, semi-cascade, raft, literati, and group/forest.
- The formal upright style, or Chokkan, is characterized by a straight, upright, tapering trunk. The trunk and branches of the informal upright style, or Moyogi, may incorporate pronounced bends and curves, but the apex of the informal upright is always located directly over where the trunk begins at the soil line.
- 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 (typically due to erosion or another natural force) and branches along the exposed side of the trunk, growing as if they are 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 higher up on a long, often contorted trunk. This style derives its name from the Chinese literati, who were often artists, and some of whom painted Chinese brush paintings, like those found in the ancient text, The Mustard Seed Garden Manual of Painting, depicting pine trees that grew in harsh climates, struggling to reach sunlight. 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 more than one tree (typically an odd number if there are three or more trees, and essentially never 4 because of its significance in Japan) 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 root-over-rock style, or Sekijoju, is a style in which the roots of a tree (typically a fig tree) are wrapped around a rock. The rock is at the base of the trunk, with the roots exposed to varying degrees.
- 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 root system, and it actually is one single tree. All the trunks form one crown of leaves, in which the thickest and most developed trunk forms the top.
- The growing-in-a-rock, or Ishizuke style means the roots of the tree are growing in the cracks and holes of the rock. There is not much room for the roots to develop and take up nutrients. These trees are designed to visually represent that the tree has to struggle to survive.
Indoor bonsai are bonsai which have been cultivated for the indoor environment. Traditionally, bonsai are shaped from temperate climate trees grown in containers but kept outdoors as they require full sunlight and a winter dormancy period at near-freezing temperatures. Kept in the artificial environment of a home, these trees will become weakened and die. However, some of the most outstanding plants used or bonsai, members of the genus Ficus, are frost-sensitive and hence not capable of being grown all year outside in cold climates.
For indoor gardens bonsai-growing techniques have been applied to tropical plants that do not require dormant periods. Because bonsai are rooted in small pots, drought-resistant houseplants are best suited for indoor bonsai cultivation.
Bonsai vs. other forms of house plant
Compared to the usual potted house plant, bonsais are rooted in a much smaller amount of soil. Consequently, they require more frequent watering. This form is therefore best suited for drought-resistant species. Compared to usual house gardening, bonsais require a lot more pruning, both of branches and roots. This often requires a significant shift in attitude for house gardeners.
The spiritual benefits of bonsai cultivation, in Japanese bonsai no kokoro are available equally to classical and indoor bonsai gardeners.
Indoor vs. traditional bonsai
The largest difference between indoor and traditional bonsai is, of course, the enjoyment of an attractive, fully leaved plant in winter instead of a dormant, leafless tree. Other differences include the faster growth rate of tropical plants, which accelerate all steps of the bonsai evolution. Moss covering, highly valued by bonsai amateurs, will not survive indoor conditions.
Tropical plants suitable for indoor bonsai
The creation of bonsai is limited only by the imagination and talent of the gardener, although some species are much more suitable than others. Members of the genus Ficus are among the most verasatile, while many succulents can be grown in a similar fashion. Here is an incomplete list of the most popular species.
- Ficus benjamina: the Weeping fig is a popular indoor tree that lends itself to the classical, upright form. It is one of the few tropicals that are accepted as "true" bonsai. The miniature cultivars like 'Too Little' are well suited for bonsai. It forms aerial roots and can be shaped as a banyan tree. Ficus are intolerant to branch down-pruning; one must start with a small tree and keep it small. They are sensitive to stress.
- Ficus neriifolia : according to Jerry Meislik, "the most useful fig for bonsai is the willow leafed fig . The small leaf is in excellent scale for bonsai and the tree has good branch ramification, good basal rootage and excellent aerial root formation."
- Schefflera arboricola: the Hawaiian umbrella tree is a popular, hardy houseplant that is ideal for irregular, banyan or roots-on-rock forms. Since it can sprout on old wood, an old specimen can be pruned back to a stockier shape with thick trunk and roots. It tolerates root exposure very well, is drought-resistant and requires a moderate amount of light. Under high humidity conditions, it produces aerial roots and can therefore be shaped as a banyan tree.
- Crassula ovata: the jade plant is a very robust and drought-resistant house plant. The miniature cultivars like the baby jade plant (C. ovata arborescens) is considered the best plant for a first bonsai. This plant will sprout on old wood. Thus, an old specimen can be pruned back to a stockier shape with thick trunk. It is kept dry in winter, placed outdoors in summer for full growth. Its roots are thin and cannot be exposed.
- Portulacaria afra : the dwarf jade looks a lot like a baby jade plant and is used similarly.
- Dracaena marginata: the dragon plant has an interesting palm-like shape. It can sprout on old wood. It does not tolerate root exposure.
- Zygocactus: the holiday cactus does not have a real trunk but easily lends itself to a cascade-type bonsai shape. It tolerates shade, not drought.
- Small succulents may be used as accent plants :
- Rhipsalis (Hatiora) salicornioides