An Introduction to the Japanese Art of Dwarfing: Bonsai

Bonsai is the term universally used in Japan for the artificially dwarfed trees and shrubs which are an integral part of the domestic, artistic and horticultural life of that country. There it is unusual to enter any house, from the palace in the capital to the poorest hut in the village, without seeing at least one specimen.

It must be realized that in the space at my disposal it is possible to deal only with the rudiments of the art of dwarfing and training. It must also be recognized that those of us who start training Bonsai straight away can never produce the wonderful classical specimens which have come down through many generations of experts, for many of these priceless little trees are two, three and even five hundred years old. These remarks, however, should not deter anyone from trying their hand. Charming little trees can be produced in a few years, and there is no doubt that an absorbing new interest will have been found.


Oval, oblong or round shallow pans are the most suitable containers. These should be of the simplest design, glazed outside and entirely devoid of any decoration. The colours which the Japanese favour are always low-toned: cream, buff, smoke-grey, reddish brown and various shades of subdued grey-blue. These cannot be obtained ready made in this country, but so many amateur potters are now available that it should not be unduly difficult to procure suitable containers. The oval and oblong pans are made in many sizes and, all follow roughly the same proportions. The inside measurements of two run as follows: (a) 9 in. x 5 in. x 2 in.; (b) 12 in. x 8 in. x 2 in.

The shallowness must be specially noted; if smaller pans are to be used, they must be even more shallow. The round pans (or shallow bowls) may be of any size, but must never be deep; one of 12-in. fiameter should not be more than 2 in. deep. All containers must have one or more drainage vents, according to size. A narrow rim not more than -1/2 in. high should surround the bottom of the pans to give them a slight lift to ensure that the drainage vents are clear of any obstruction.


This is probably the most important single factor in the cultivation of Bonsai. These plants need plenty of water, therefore the drainage must be perfect. Unless water soaks away rapidly from the surface of the soil, there is sure to be trouble owing to rotting of the roots. A concave, not a flat, crock must be placed over each vent and the pan filled to one-quarter its depth with some material which will provide sharp drainage, such as very fine gravel or coarse chicken-flint grit. A very useful material which will serve a double purpose is known as Cornish sand, a by-product from china clay, obtainable very cheaply from most horticultural nurserymen or nurseries. Put through a culinary sieve, the coarsest portion gives admirable drainage, and the siftings will be found more satisfactory than silver sand in the compost. The gritty drainage material must be covered with a film of spent hops or granulated peat. This must not form a soggy mass; only sufficient is required to prevent the compost washing down and clogging the drainage.


A suitable basic compost is composed of 2 parts of old fibrous loam rubbed down between the hands, 1 part of flaky leaf-mould put through a medium sieve, 2 parts of coarse sand and a dusting of steamed bone flour. For conifers another 1 part of sand is required.


Having crocked the pan and prepared the drainage as described, a layer of compost must now be added. The depth of this must be governed by the depth the roots of the plant require. The base of the trunk must not be covered, in fact, if the tree can be so planted as to show a short length of the thickest root as they spring from the base of the trunk, so much the better. The tree must be planted at one end of the pan, the roots carefully spread out and the soil worked among them. The tree should stand sufficiently high for the soil to be drawn up to it in a mound. The effect of this slight rising is much more pleasing than if the surface is uniformly level. When planting is finished, the soil should be firm but not tightly rammed down.

Root Pruning

The roots of cherries can be cut back even harder, after which they should be given a year in the open ground to develop a strong system of fibrous roots. If after this period the roots are found to be too big for a pan, they may. The roots of pines must never be cut, as these trees easily bleed to death. Sufficient dead roots will always be found to keep root growth in check; these should be gently pulled away. Over-long healthy roots must be wound round the base of the trunk and tied in a knot.

Pruning and Shaping

Whether dealing with branches or roots, it must be remembered that these must always balance each other. Too much root will speedily lead to long, soft top-growth, and consequent difficulty in restoring proportion and shapeliness; too much top growth will eventually spell death if the roots are not large enough to provide adequate nourishment.

The training of Bonsai requires endless patience, constant vigilance, neat, capable hands and a faultless eye for line. As to the shaping of the trees, two methods may be followed: which is decided upon depends on the shape of the raw material or upon the taste of the trainer. Seedling trees of 5 or 6 in., which can often be collected in woods or well-furnished gardens, frequently assume a good shape naturally, and require little shaping beyond occasional pinching out of superfluous growth buds. Strong, healthy seedlings which show no promise of natural shapeliness should be pruned. This is where discrimination and sense of line are necessary, for it is easy during these early years to make or mar the specimen. This method of training, if skilfully carried out, will produce delightful little trees of considerable character after a few years.

Many Japanese trainers prefer the more artificial style of training with the aid of wire. Again a critical sense of line is called for here, combined with extreme neat-handedness. The work should be carried out at that season when the tree in question is in its most pliable condition, as it will be subjected to considerable strain. A copper wire of medium gauge is used for young trees, a thicker one for more mature specimens. Beginners are advised to become accustomed to the use of medium gauge, as the thicker wire will probably require to be annealed before a novice can use it. The wire must be secured at the base of the trunk or branch with a gripping hook, which must not be so tight as to damage the bark or constrict the flow of sap. It is important, however, that this grip does not slip. The wire is now wound upwards in regular spirals round the limb, taking care that the coil, while giving support, does not pinch anywhere. When the spirals, which should be about an inch apart, are completed, the wire must again be securely fastened. Unless the wire is secure at both ends, the spirals will loosen as soon as bending is attempted and the wiring will have to be done again. Once the spirals are firm, the trunk or branch can be very carefully bent into the required curves. These must be smooth and flowing. The trainer must be prepared to give time to this matter, going over the limb again and again, using the balls of the thumbs to gently persuade the wire and wood to take the desired shape. The wired limbs must be constantly watched, especially if the tree is making growth. If the wire becomes too tight, it must be taken off and replaced with more loosely wound spirals. In a year or two the wood will become hard and the curves permanently fixed. The wire can then be dispensed with altogether.


Bonsai in the making must be transplanted every spring until they have attained the desired shape and height. It is best to start them in the smallest-sized pots into which the roots will fit, allowing a small amount of space for root-growth. Pot them on gradually until a strong system of fibrous roots has developed. The tree is then ready to be transferred into a pan. If a tap- root has developed, cut it back half-way and remove it completely the following year. If there is plenty of fibrous root one or two of the secondary hard roots may also be cut out. The objective at which to aim now is to get the tree growing entirely on fibrous roots. Once the tree is established in the pan in which it is destined to spend the rest of its life, the fibre roots must be kept in check. This is done when the tree is transplanted. The tree is taken from the pan and some of the loose soil is shaken out of the ball of roots, leaving the outer fringe of roots fully exposed. With a sharp pair of scissors clip all round the ball until it will fit back into the pan with a little space to spare. Courage is needed the first time this is done, but confidence comes with experience. Wash the pan, prepare it as described, replace the tree; and work fresh compost firmly round the roots. Water, and keep the plant out of the sun and wind until it can be seen that growth is re-established.

19. April 2017 by Dave Pinkney
Categories: Bonsai, Bonsai Care, Propagation, Training/Pruning | Tags: , , | Comments Off on An Introduction to the Japanese Art of Dwarfing: Bonsai


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