Bonsai

by Lindsay Farr, Bonsai Farm, Swan St, Richmond, Melbourne

Bonsai is the art of training young seedlings or cutting grown plants, or the sculpting of established plants to represent miniature trees. These living, artistic, container grown trees  are an ideal way to have a garden in miniature, and they will create much interest among your family and guests.

Bonsai growing is a leisure pastime that places humans as one with nature. Elements of nature, such as wind, lightning, snow, the blazing sun, seasonal changes, in fact most of natures many faces can be shown or implied in miniature by the use of imagination and basic gardening skills. Wind might be implied by way of creating a leaning trunk or branches growing horizontally in one direction. Light can be suggested by carefully peeling away the bark at the highest points of upright trees to imply that these tips have been struck during a storm. A lake or the sea can be implied by artistically placing small pebbles and sand on the soil surface near the rim of the bonsai container creating a miniature beach suggesting water.

The basic techniques involved in the training of bonsai trees are feeding, pruning, wiring, bud pinching, and careful watering.

Root Pruning and Potting-Up Bonsai

The primary function of pruning the roots of a bonsai tree is to ensure the health of the tree. Since the roots of the tree are restrained by it's container they tend to wind round and round the inner surface of the container, which compacts the soil, thereby depriving the plant of air and water. If these long roots are 'teased' away and removed with sharp trimming shears then air and water can circulate freely through the soil/potting mix. Root pruning and re-potting of bonsai is generally carried out from late autumn to early spring. Some form of protection from extreme cold should be provided if it is done in winter.

When potting up use some shade cloth or fly wire to cover the drainage holes in the container. A coarse component of your potting mix, or some small pebbles should cover the shade cloth or fly wire to help provide good drainage. Potting mix can then be applied to cover the pebbles.

The tree to be planted should have any dead roots removed, and some of the healthy roots should be teased out from the root ball. The tree can then be positioned as desired in the container. Fresh potting mix can now be filled into the pot, and using a chopstick or similar implement can be lightly compacted around the root ball. Water the pot thoroughly, then plant moss on top of the potting soil. If the tree is top heavy you made need to wire it in position until it has established.

Bonsai Pots/Containers

Bonsai can be grown in a wide variety of containers, but are most commonly grown in small shallow dish or bowl shaped containers. Ceramic, glazed or unglazed, is the most widely used material. Pots made specifically for bonsai are readily obtained from bonsai, and some of the larger general nurseries.

Potting Mixes For Bonsai

Drainage, water retention, aeration, and nutrition levels are all important factors in choosing a potting mix for your bonsai. To ensure good drainage, yet still retain sufficient moisture for healthy plant growth try a mixture of mulch consisting of well rotted compost or animal manure, or fine pine bark, in equal parts with clay grit. The clay is best collected in a dry state as the granular structure of the clay is preserved. The fine powder and larger lumps are sieved and discarded, then the remaining granules mixed with the mulch. If the clay does not contain a reasonable gravel or grit component, this can be added separately. At this stage fertilizers, and trace elements can be added. Mixes containing coarse pine bark, or high percentages of sandy soils should be avoided as they generally give poor results.

Wiring Bonsai

Bonsai trees are wired to control the direction of growth of a branch, twig or trunk. The most common use is to direct upward growing branches downwards to give the impression of great age. Copper or aluminium wire with greater bending resistance than the desired branch is normally 'anchored' around the trunk then neatly wound to the end of the branch.

Wiring is best done when the tree is in a semi-dry condition as the woody parts are flexible to bend without causing major damage. The wire should not be wound tightly around branches as this can cause damage. Bending of branches should be done very carefully. For thicker branches it is best to bend the branch in the desired direction as you wire it.  Wires should be removed before branches thicken. For young vigorous trees wires should only be left in position for a few months. For older established trees it can sometimes be left for several years. Wires can also be used to pull branches down by anchoring one end of the wire to the container.

Top Pruning

For the development of a medium or large bonsai tree a young tree may be allowed to grow vigorously then cut back hard annually for several years to develop a strong trunk and basic shape. Then  a more regular trimming program can be undertaken to develop twiggy branches. Most deciduous and hardwood varieties can be cut back to old wood and still shoot new growth, however care must be taken when top pruning conifers as many will not shoot from old wood. The most effective way to prune conifers is to pinch out the tips of new growth. This technique is also used for broadleaved plants such as azaleas, maples, elms, oaks and beech. As soon as the new shoots have opened out to two or three leaves repeat the process. A sharp pair of trimmers should be used to make a clean cut. Do not use fingernails.

Feeding Bonsai

Proper nourishment is essential for healthy growth of bonsai trees. Plants are generally fed from early Spring through Autumn. A five to sixth month slow release fertiliser such as Osmocote provides a convenient single application method. If this method is used be sure to lightly bury the fertilizer pellets below the soil surface, or under moss, so they can't be seen and to help fertilizer retention. Liquid fertilizers, such as fish emulsion can be applied every few weeks.

Watering

How often you water will depend on a variety of factors, including weather conditions, the season of the year, the type of plant being grown, the type of container used, and the moisture holding ability of the soil/potting mix. Experience is the best guide to when you should water. Don't be misguided by a lush covering of moss on the surface of the container. Mosses can stay green for long after the pot has dried out. The plants can be easily watered from above with a fine rose watering can or hose. For bonsai that are planted with the soil level with or mounded above the top of the container repeated sprinkling of the container is required. An alternative means of watering is to submerge the container in another container filled with water, being careful not to dislodge the soil/potting mix. When air bubbles cease rising then the plant should be thoroughly watered.

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