Styles of Bonsai

The categories of bonsai styles have been based on specific elements in nature. Often the names of the styles explain the origin of the design and its aims: slanting style, for example, gives the effect of a tree exposed to strong wind, the trunk leaning at an angle. Some trees suggest a style – Picea abies, the Norway spruce, naturally looks formal and upright, whereas an oak grows best in an informal arrangement. Most trees and shrubs that are suited to bonsai can be developed in any of several styles.

Design Principles

A bonsai design encompasses the style and condition of the tree; the container's size, shape, and finish; and the relationship of tree and container. Some basic elements apply to all bonsai, the main ones being root spread, trunk form, and the arrangement of branches.

Root Spread

In both nature and bonsai, an interesting root formation exposed above the soil gives a sense of maturity and stability, whereas a young tree's roots are typically concealed beneath the ground. Ideally, roots should extend in all directions from the trunk, but need not be evenly spaced or arranged symmetrically, as long as there is a good visual balance. Roots can give a naturalistic impression of stability and balance, even though they are heavier on one side of the tree, or their complex textures and divisions can break up the tree's structural lines. The way the roots connect to the trunk, whether they radiate or flow from its base, or seem a firm anchorage, forms another natural and artistic element of bonsai design.

Trunk Form

Bonsai trees may have straight, curved, angled, or divided trunks, just as trees in the wild do, but the most important trunk feature is a good taper, with the diameter diminishing smoothly towards the top. Thickness at the base adds to an impression of age, but a parallel trunk line passing into the tree's apex destroys balance. The trunk's thickness should suit the specie's characteristics, whether a delicate maple or a heavy oak. Some trees need several years of growth and training to develop an ideal form.

It is also important to see the trunk, even if the foliage masses cut across it; a trunk's shape, bark texture, and color add character. A very aged or weathered trunk can be an advantage, but avoid a tree with a distinctly scarred trunk unless it can be made a feature.

Branch Arrangement

Branches form the basic structure of a tree's silhouette. Their arrangement as they emerge from a bonsai trunk should be well balanced, in harmony with the general character of the tree, and visually complementing the trunk line. You can adjust the outline and structure quite radically by pruning and wiring, but you must remember the following basic rules when considering a tree or shrub for bonsai.

A spiral staircase is a good model for the ideal arrangement of branches, creating a balanced, although not necessarily symmetrical, pattern around and up the trunk. The first branch should be roughly one-third up the trunk, with the heaviest branches at lower levels. Branches are usually thicker near the trunk and taper along their length. Bonsai trees are normally pruned to an approximately conical spread, with the most delicate twigs at the top.

Balance and Harmony

Careful training of the shape and structure of a tree, and detailed consideration of the relationship between it and its container are necessary to create a well-balanced design. This Japanese white pine, Pinus parviflora, is an excellent example of a successful bonsai.

Branches at the apex are pruned more closely; sometimes the lower branches may extend quite far before being pruned, so they thicken at the trunk. Prune out branches that cross, spread out from the same point on the trunk, or grow directly opposite one another. Wiring can often adjust a branch's position to fill a gap.

The Front View

Bonsai are always designed with a “front” view, or preferred viewing angle, even though they can be viewed from all sides. A bonsai should be viewed with eye level corresponding to a point about halfway up the trunk. It should highlight the most attractive branch arrangement, allowing you to “look into” the tree while creating a pleasant silhouette. The front view should let you see the most pleasing part of the roots, and the most graceful angle and best taper of the trunk.

Curves in the lower part of the trunk can be best seen when they veer to one side, not toward the viewer: a tree with a forward curve is called “pigeon-breasted”, an undesirable trait. Only the upper third of the tree should contain branches that grow directly forward; to achieve depth and perspective, branches at the back should extend away from the viewer. Beginners who study photographs instead of live trees make the mistake of neglecting the back branches, invisible in photographs. The apex, or top of the tree, should incline towards the viewer, or “bow” to you, as the Japanese say. An apex leaning away never looks right.

Choosing the front view means assessing roots, trunk, apex, and branches from various angles to find the best combination. Pruning and wiring can adjust the apex and branches, so the trunk and roots are more crucial to your decision; the most critical are the roots as they are most difficult to change.

Bonsai Sizes

Bonsai is not about “making trees small”: the tree is smaller than in nature mainly to make it more convenient to work on. Sizes range from a tiny tree that you can balance on your hand to one taller than a man. Most bonsai fall within a middle range of 6 inches (15 cm) to 2ft (60 cm), because very large or very small specimens present special problems.

Large trees, over 6.5ft (2m), are impressive, but difficult to transport safely, or even to move for grooming. There is also the expense of a large container, and the problem of where to display them. Very small trees in tiny containers may need watering several times a day in warm or dry weather. Design is also difficult: in a medium-sized bonsai, one leaf may represent a cluster of leaves in scale with the natural size, but one leaf in a tiny tree must represent a branch or whole apex. You may be able to represent only two branches and the apex – very small bonsai require a minimalist approach with the principle of “less is more”. However, the scale of miniature bonsai (also called mame bonsai) does allow a large collection to be housed in a limited space.

A Sense of Scale

Whatever size your bonsai, its scale must create a realistic impression. Small-leaved trees are more adaptable in terms of scale. The larger a tree's leaves and the coarser its foliage and twigs, the more difficult it is to make them represent a full-sized tree. Some trees are simply not adaptable to very small bonsai; others are quite unsuitable for extra-large specimens; but many species grow readily as medium-sized bonsai. There is often more scope for adjusting the sense of scale in group and landscape plantings, where the trees relate to each other and to the added rocks or ground-cover plants.