How Bonsai Works

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Bons­ai is the ancient art of discovering and honoring nature by rendering it in miniature. Unlike model trains or dollhouses, bonsai is a living landscape. It is the vision of the bonsai artist applied to a tree, shrub or plant.

In Japanese, bonsai literally means a plant in a tray [Source: USBonsai]. This describes the complex relationship between the bonsai tree and its container, because the right container contributes to the visual harmony the bonsai artist is trying to create. Bonsai captures the true spirit and character of the tree within the confines of a shallow pot.

Imagine a woodland scene. The picture that just flashed into your mind probably brings with it specific sense memories. You may have remembered the sound of birds singing or the feeling of the breeze on your skin. You may have recalled the sound of leaves rustling in the trees or the smell of moist wood and wet earth. These cues add depth to your recollection. Bonsai is like that: A bonsai tree is raised and trained through careful shaping and pruning to recreate the essence of woodlands, meadows or any other natural setting.

­­At first, this seems like an imitation of nature because it involves wire shaping, drastic root trimming and regular pruning, but the beauty of bonsai is that it is natural. The actual meadow tree or woodland bush is sculpted to bring out its exceptional qualities. Bonsai blends art with horticulture in a way that makes it a satisfying hobby for both the novice and seasoned bonsai enthusiast. It has facets that appeal to the naturalist, plant lover and dedicated artist, and exploring the many facets of bonsai can become a lifelong passion.

In this article, we'll explore the art and craft of bonsai, starting with a glimpse of its historical past.

The Beginnings of Bonsai: Bonsai History

Bonsai probably originated in China, where it was first called pun-sai (tray plant) [source: Lesniewicz]. Chinese tomb paintings from the Tang dynasty show trees in shallow pots, and we can intuit that the art of bonsai-like plant sculpting is at least that old. Some speculate that its roots in China may go back as far as 206 B.C. and still survive today.

­From China, bonsai migrated to Japan, possibly through trade or as an exchange of cultural gifts, where by the 13th century it was an established art form. The Japanese refined and perfected bonsai, developing many of the aesthetic principals that are observed today. They also introduced specimens of their unique art to the West in the early part of the 20th century.

At the Paris World's Exhibition of 1878, and later at the London Exhibition of 1909, bonsai became a sensation, and specimens were actively sought for private collections [source: Jahn]. Some of the original specimens were even purchased at auction for very high prices.

After the Second World War, bonsai became more accessible to the average enthusiast, and as supplies have become less expensive and more plentiful, the hobby has become more popular, expanding to include plant species and design choices unimagined a few decades ago. Next, we'll look at the many styles of bonsai and how they express the diversity of nature.

Styles of Bonsai

The goal of bonsai is to create a pleasing specimen that reflects nature as much as possible. This can be an idealized view of nature, or a vision of a more matured, weathered tree that has survived for many years. In styling bonsai, scale is important, as are perspective and symmetry. Different styles of bonsai can represent stately upright trees, trees struggling in the wind, trees with branching trunks and trees that can be grouped to create the look of a forest or copse. Each arrangement is paired with a corresponding bonsai pot that will complement its design. The following established styles of bonsai have very different looks.

  • Upright (Chokkan) is a formal bonsai style incorporating a classically balanced triangular shape, single straight trunk and branches arranged in threes.
  • Moyogi is a less formal upright design that still has a relatively straight silhouette, but can have more sinuous features in the trunk and branches.
  • Slanting (Shakan, Fukinagashi) style bonsai is noted for its leaning trunk, which grows at a 45 degree angle to the base of the tree. The branches will follow the angle of the trunk, with the balancing first branch jutting in the opposite direction in the Shagan style.
  • Cascade (Han-Kengai, Kengai) style bonsai often resembles a lone tree clinging to the side of a rock face that is buffeted by the wind. The lone cypress appearance is dramatic, and showcases the essential value of the appropriate pot in bonsai. Cascade bonsai requires a deeper pot to offset the inherent weight imbalance in the design. This design can either be extreme, with the foliage extending below the rim of the pot (Kengai) or modified to bend parallel with the rim (Han-Kengai), like a tree extending partly over a the side of a cliff.
  • Literati (Bunjin, Bunjingi) style of bonsai is characterized by its focus on perspective. Imagine a tree on a mountaintop viewed from below. The long, narrow trunk and spare top foliage of the literati style recreate that vision of telescoping distance. The sense of height is also emphasized by the use of a small oval or round pot.
  • Broom (Hokidachi) style creates the symmetry and balance of a half-crescent of foliage fanning from a single, straight trunk.
  • Landscape (Saikei) style creates the optical illusion of a miniature scene, complete with rocks, mosses, grasses and even a water feature.
  • Root Over or On Rock (Sekijoju, Ishitsuki) style uses the coiling roots of some tree varieties as design elements, training them over or into rocks as part of an exposed, graphic and rugged structure.
  • Multi-Form (Sokan, Kabudachi, Ikada, Yose-ue) cultivation techniques create an illusion of multiple trees from a single root, or include the actual addition of a number of trees in the same pot. The result is a forest or glade rendered in miniature.

Guiding a tree through life in a pot has its challenges. Next, we'll look at some of the secrets of cultivating bonsai.

Cultivating Bonsai

A larger bonsai tree kept outdoors.
A larger bonsai tree kept outdoors.
Stephen Schauer/Lifesize/Getty Images

Displaying a bonsai tree to advantage requires manipulating its component parts. Sometimes this manipulation is to keep the tree small, other times it is to create the illusion of a much larger, older tree or a tree with a distinct style. This is the artistry of bonsai at work.

Almost any tree, shrub or plant can be used for bonsai, but the best candidates are trees and shrubs that have small leaves or needles and are naturally dense or compact. Small leaves, a dense habitat and woody stems help maintain the illusion of scale, while temperate plants are the easiest to care for.

Refining the tree's structure starts with the roots. A portion of root visible at or above the soil line helps to create the illusion of age and weathering and is a desirable feature in bonsai. Exposed roots work with the trunk to produce an interesting composition. The trunk itself may be smooth or gnarled, creating character and drawing attention to its interesting features, but it should always have a smooth taper toward the top. The shape of a bonsai's trunk can be controlled through grafting and wiring, and while young, may be shaped to influence the structure of the tree.

­­Shaping is one of the fundamental tasks of bonsai cultivation. Beginning with a vision of the finished tree, the bonsai artist starts the long task of shaping the tree by carefully altering its branches. In bonsai design, a tree's branches provide symmetry to the whole and are manipulated through wiring and pruning to realize that original vision, both in scale and proportion.

This process can take many years, and in the case of some deciduous trees, requires the removal of all of the foliage from time to time. Wires can be left in place for a year or more and are carefully removed before they can score or harm the growing branches. Bonsai trees should always be balanced and harmonious. No branch should completely obstruct another. The aim is to fashion a tree in which each branch makes a contribution to the whole while never obscuring another branch. In this scheme, branch shape, root and trunk structure, and the color and shape of the foliage create a cohesive whole.

Now that you understand a little about cultivating bonsai, let's explore some things to look for when buying a bonsai tree.

Buying Bonsai

Your best bet to find a good bonsai tree is to visit a respectable nursery.
Your best bet to find a good bonsai tree is to visit a respectable nursery.
Hoang Dinh Nam/AFP/Getty Images

There are many good candidates for bonsai at any tree or plant nursery, but it may take years, if not decades, to achieve the desired results. In spring, there are many nursery specimens to choose for bonsai. These very young trees and shrubs will be starting their seasonal growth cycles and can make excellent candidates for new bonsai stock. If possible, choose specimens with straight, tapering trunks, or for a more unique look, the beginnings of an interesting bend or knot that can be used in your design. Remove any dead leaves or needles to really inspect your potential choices. Many of the branches will have to be cut to create the initial design, so try to look at the structure of the trunk and major branches to get an idea of the basic shape of the tree. It will help for you to have an idea of the type of bonsai style you want to create. This will give you an idea of the best starting stock to choose.

For a trained specimen that has already been started in classical bonsai style, there are some qualities you should look for. Bonsai trees can vary in price depending on the species of plant, its age and its artistic or aesthetic value. Many of the most valued bonsai plants are never offered for sale, but pass privately from hand to hand.

­­When you shop for bonsai, you will probably have a selection of relatively young plants and a range of styles and varieties to choose from, including deciduous trees, evergreens and flowering trees. There are a few qualities all these plants should have in common. First, they should always come from a reliable supplier. Dealing with an importer or retailer who understands bonsai is a good first step in acquiring a superior specimen. The second step is to inspect any potential purchase carefully. Make sure that the plant shows no signs of disease or insect activity. Verify that the soil is evenly moist and packed firmly around the roots of the plant. A robust bonsai will show vivid foliage when in season.

Look for specimens that appear old. The appearance of the roots and trunks of these trees will often give the impression of age by their texture, contour or coloring. These plants have greater value and aesthetic appeal. Standing at the front of the plant, make sure the branches radiate to the sides and back, not forward. Check the trunk, and pass on any trees with distinctive old scarring from removed branches. The overall appearance of the plant should be in proportion and be enhanced by its pot. It should look vigorous, healthy and balanced, both up close and at a distance.

In the next section, we'll talk about starting a new bonsai tree.

Starting Your Own Bonsai Tree

A bonsai tree
A bonsai tree
Stephen Schauer/Lifesize/Getty Images

­Although a bonsai tree can be grown from a seed, started from a cutting or harvested in the wild (in areas where you can get permission to do so), the most common way to obtain a new plant for bonsai is through a reliable nursery. Start looking for a tree or shrub for bonsai in early spring. Choose a specimen that is 6 to 8 inches tall (15 to 20 cm) and has a strong, tapered trunk that is free of scars and blemishes [source: Lesniewicz]. The style you have in mind for your new bonsai tree, like upright, slanted, cascade or another traditional form, will help you select a plant variety with a good basic shape and the characteristics you need. Pruning and wiring bonsai is usually started in the second year and onward, but selecting a good basic shape will save you time and extra work later.

Choose a pot that will complement the color of the foliage and balance the tree's emerging design. Bonsai pots are typically shallow and always include drainage holes. The pot and tree work together to create the bonsai design, and although a bonsai tree may be planted in many pots during its life, each pot helps create balance and harmony in the overall design.

After choosing a specimen, potting the young tree is the first step in transforming it into bonsai. The following steps will help you turn a tree, shrub or other plant into a bonsai-in-training. The process of growing a true bonsai will take years, but these first steps are important because they will help your tree adjust to a shallow pot and a smaller root system.

  • Make sure the young plant is well-watered before potting.
  • Prepare the pot by feeding a length of small gauge bonsai wire through the drainage hole to support the tree until it becomes established.
  • Place a thin layer of gravel in the bottom of the pot for drainage, temporarily blocking the drainage hole if too much gravel escapes.
  • Remove the bonsai tree from its old pot, and remove the soil from around the roots. A bonsai root hook and rake can help make this part of the process easier.
  • Inspect the roots, discarding any dead or damaged bits.
  • Trim the roots by about two thirds. This seems extreme, but controlling root growth is an essential element in creating and maintaining bonsai. Given time and care, the tree will adjust to its new circumstances.

To continue with water, soil and sun for your bonsai, head over to the next page.

Giving Your Bonsai Tree Roots

Once the roots are trimmed, you're ready to give life to your plant.

  • Place a layer of bonsai potting soil over the gravel in the pot. There are prepared mixtures you can use, but if you want to experiment with your own, bonsai soil is usually composed of equal parts sand, peat and loam. It's important to understand the requirements of the specific tree you have selected for bonsai to know the soil mixture to use. Achieving the proper chemical balance in the soil will be important for the healthy growth of your bonsai tree.
  • Spread the trimmed roots of the tree evenly around the pot and use the wire to hold the tree's trunk in place. You'll be removing the wire later, so keep the wiring simple. It's easy to damage the trunk and roots when wiring the tree in place, so use caution to turn the wire carefully.
  • Fill the pot to the rim with soil, tapping the pot a few times to level the soil and remove air pockets. Firm the soil in place around the base of the tree and then out to the edges of the pot. The soil should reach the very top of the pot when you're done, and the crown of the tree, the part where the trunk stops, should be at the soil line.
  • Place your new bonsai tree in a shady spot for a week to allow it to adjust to its new pot and shorter root system. Be sure to remove any covering you placed over the drainage hole before you water. Move the tree into a sunnier location gradually. Start with a couple of hours of morning sunlight about a week after potting and work up from there.
  • Now that the roots of the tree are shorter, it's important to provide water to the tree regularly. Many bonsai trees need soft water that's tepid, not cold. Be sure that water is draining from the pot after each watering. Allowing a bonsai tree to sit in water for an extended period will result in rotted roots and the death of the tree.

You must provide those things that your new bonsai can't get for itself. In nature, the roots of trees are protected in winter with a thick layer of soil. To keep your bonsai safe from weather extremes, you must keep it in a greenhouse or provide it with a protective enclosure or insulation. Another area in which your bonsai differs from a tree in nature is that it can't send its roots deep into the soil to look for water. Providing enough water is an important function of keeping a healthy bonsai tree. It's a commitment, almost like keeping a pet, because some bonsai trees need to be watered often in hot summer weather. When your tree starts to take shape, your efforts will be rewarded.

For more useful tips and tricks on keeping your bonsai tree healthy, take a look at the next section on caring for bonsai.

Caring for Bonsai

A bonsai tree behaves in a pot much as it would in nature. Deciduous trees change colors and drop their leaves, fruiting trees bear fruit and pine trees drop needles. Their requirements don't change as much as you would expect to accommodate the fact that they're living in the confines of a shallow container. The most important factors to consider when caring for bonsai trees are water, light, soil and nutrition. These elements work together to maintain healthy bonsai plants that will flourish from year to year.

  • Whereas a tree in nature can spread its roots many feet in every direction to search for water, a bonsai has to have water provided to it on a continuous basis. Shallow bonsai pots can lose moisture rapidly, so consistent, regular watering, sometimes more than once a day in summer, is necessary. Bonsai have different water needs at different times of the year, so observing a plant's habits is important. Test the soil in the pot daily. It should remain moist, but not soggy. Water bonsai either in the morning or evening, possibly both during the hottest part of the year. If possible, avoid using chlorinated water for bonsai trees. Rainwater is an excellent choice and can be trapped in a bucket and used when needed.
  • Light is a source of nutrition to all plants, and offering bonsai enough of the right light is as important as providing it with enough watering. Knowing the light needs of a particular plant species will offer invaluable information about how to care for it. Bonsai also needs balanced light to develop evenly. When positioning bonsai, take care to provide them with equalized light or rotate them often to achieve the desired results.
  • Beyond water and light, bonsai rely on the right soil to survive. There are many theories on the best soil mixture for bonsai, and different varieties have specific needs that should be considered. The goal of bonsai soil is to be dense enough to retain moisture to feed hungry tree roots while draining fast enough to keep the roots from being harmed by standing water.
  • The interaction of water and soil helps deliver nutrients to feed bonsai tree roots. Supplementing this nutrition with fertilizers helps keep bonsai trees in top condition. Although fertilizer can be fed as a liquid, powder, a firm cake or granules, it's important to monitor its absorption to know when additional feedings are needed. This can be done according to a set schedule, or as the result of careful observation of the plant.

Part of caring for a bonsai tree is being observant of any changes in the plant. Small changes can be a signal of problems that need attention. Pests and diseases afflict bonsai as they do other plants in nature. The good news is that bonsai are hardy and can often recover from infestations, but catching them early is important.

When enjoying bonsai, watch for small spots of spit on leaves that signal the presence of the larvae of spittlebugs, or the black or red dots of mites that can appear on tree bark. Both of these can be wiped off or brushed away. More persistent insects like sap-sucking scale insects or aphids that leave sooty or sticky residue can be treated with insecticide. Other insects, like weevils, leaf miners, snails and caterpillars, inflict damage to leaves that will be easy to recognize.

In the next section, we'll talk about pruning and shaping bonsai to expose its beauty.

Shaping Bonsai

Bonsai trees require regular pruning and shaping, even after a desired effect is achieved. Good, healthy growth is a sign that a bonsai is in good condition and happy with its care and location. It also means that some maintenance work is in order. This can be as easy as pinching back new growth on an established tree, or as extensive as shaping, wiring and cutting a young tree as part of its first styling.

Although there's no set style or design that a tree or shrub must take to become bonsai, the overriding principle is to create a small representation of the tree in nature. More natural forms are preferred, although artistic manipulation is freely used to make bonsai trees look older or weathered, or to showcase unique but natural elements like knots or roots. This creates additional interest and helps to remind the viewer that the bonsai tree is a product of nature, and that wind, hot summers, droughts and other natural occurrences have helped shape its appearance.

If we start to look at the bonsai tree as a piece of living sculpture, it's easier to understand how carefully removing branches and encouraging others to take on different shapes and angles can help enhance the look of the tree, mimic age, create balance and conform to one of the many different classic styles of bonsai. The bonsai artist uses small gauge copper or aluminum wire to carefully wrap branches and sometimes the trunk of a bonsai tree to force the pliable wood to take on new directions or shapes. The wire is monitored carefully while it's in place to make sure that it isn't cutting into the growing wood, and after a time it's removed.

Pruning Bonsai

Judicious pruning is also used to shape the bonsai tree. Sometimes the branches of young trees are aggressively but carefully pruned and the subsequent growth trained into a classic bonsai style. Other times, existing branches are trimmed carefully with viewing angle and balance in mind. Any growth that doesn't conform to the plan of the bonsai artist is removed, and the remaining branches are carefully manipulated over a period of years.

Using the right tools can make the job of pruning and shaping bonsai easier. When working with small branches, manual dexterity is also very helpful. Indispensable tools include wire cutters, long-handled pliers, nippers, tweezers, a small saw and leaf-cutting scissors. There are many other bonsai implements available, and it's true that maneuvering into tight corners in order to wire and shape branches can be much easier with the latest pruning gadget, but a little time and some patience are the best tools.

Pruning and shaping isn't just about getting rid of the bits you don't want and wiring branches in place; it's about training the living tree. This is the way that the bonsai artist works in harmony with nature to create a unique and satisfying plant, but to be successful, he must have a plan. Classical styles of bonsai can be an inspiration for the bonsai artist, but the tree itself will be the basis for his vision.

Great bonsai artists are able to see the finished bonsai tree in the fledgling young plant and cultivate it over decades to achieve that vision. For example, repeated cutting early in spring will encourage thicker growth in some trees, and the process of leaf-cutting in some deciduous trees will produce successive crops of smaller, move vividly colored foliage. Wiring over a period of months can alter the shape and direction of branches, or dead wood can be left on the trunk to make a bonsai tree look older or more weathered. These are a few of the methods employed to create bonsai, living sculpture, from a tree, shrub or other plant.

In the next section, we'll talk about ways to give bonsai trees long-term care and address the subject of enduring design.

Long Term Care and Design of Bonsai

Bonsai trees should be repotted every two years and their roots pruned and manicured. Bonsai roots must be kept short and evenly distributed across the area of the pot. In younger trees, as much as two-thirds of the root can be removed at each repotting, and after repotting, plants should be kept in semi-shade and protected from hot weather until they've had a chance to acclimate.

A bonsai tree that has weathered a number of seasons can be treated differently from a young plant. Pruning and shaping from year to year isn't as extensive, and repotting, although still performed every couple of years or so, will not require a new pot. Occasional repotting to remove excess root growth invigorates the plant while helping to retain its size and keep it in its accustomed pot.

Measures can also be taken to enhance the design and personality of an established bonsai tree and deepen the illusion of age and majesty that is prized in older specimens. Weathering a tree's trunk through bleaching (Jin and Shari), and adding an assortment of quality mosses and groundcovers like Selaginella and Crassulacea to the soil to approximate forest undergrowth enhances the appearance of an established bonsai arrangement.

The elements that distinguish a remarkable bonsai tree are subtle but profound. The subject shouldn't just look like a miniature tree; it should retain the presence and naturalness that proclaims that it's a living thing. It should carry with it an echo of its natural environment, and give the viewer an immediate sense of recognition, wonder and delight.

Visit the next section for links to more bonsai information and other great articles.

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Sources

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  • National Bonsai Foundation. "Exhibits." 2006. 9/8/08. http://www.bonsai-nbf.org/site/exhibits.html
  • Phoenix Bonsai Society. "John Yoshio Naka." 1/29/07. 9/8/08. http://www.phoenixbonsai.com/JYN.html#Foundation
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