Bonsai (pronounced bon-sigh) is the horticultural art form of training plants to look like large, aged trees that appear in nature, but in miniature. Bonsai can be developed from seeds or cuttings, from young trees and transplanted into containers. The main definition of bonsai as an outlet for both art and horticulture is quite wide. There are many myths which are associated with bonsai. These not only provide confusion for budding enthusiasts, but gives the pastime a bad name for anyone not majorly experienced in the area. A bonsai is not a genetically dwarfed plant and is not kept small by cruelty in any way. In fact, given an adequate supply of water, air, light and nutrients, a properly maintained bonsai should outlive a full size tree of the same species. The techniques of Bonsai are no more cruel than that of any other horticultural endeavour. It is also common belief that bonsai are only a few centimetres tall. This is untrue, although bonsai are small in comparison to their huge life-sized brothers, most are over 25 centimetres tall and up to 1 metre in height.
Most bonsai range in height from 5 centimetres (2 in) to 1 metre (3.33 ft). Bonsai are kept small and trained by pruning branches and roots, by periodic repotting, by pinching off new growth, and by wiring the branches and trunk so that they grow into the desired shape.
How frequently you water your bonsai depends on many things. A dry wind, excessive heat, or a combination of both, can quickly dry out the soil, so you must monitor moisture levels regularly. Generally if you keep your trees outside where rain can water them, you don't need to worry much in the winter except in times of hot weather or little rain. In the summer you should endeavour to water your plants several times a week, and daily in very hot periods where you should move the trees into the shade. You may find it is a good idea to set up a drip sprinkler system where the bonsai are watered everyday in the summer and every three days in the winter. Alternatively, you can use a watering can to water the soil and roots. Using a general water sprayer to increase humidity is also a good idea if your climate experiences dry periods.
To keep your bonsai in good shape and to maintain healthy growth requires regular feeding at the right time of year with the correct fertilizer. Fertilizer must be continually replenished due to a certain amount being washed out each time the plant is watered.
You can get many different types of fertilizers, in a variety of forms. The most common is pellet-form this is a slow-release fertilizer which will take care of feeding requirements for several weeks at a time and is probably the type of fertilizer most used by bonsai enthusiasts. Soluble powder and liquid feeds are also used for rapid effect over short-term periods. These are applied to the soil with a watering can and are used up relatively quickly.
To understand exactly how your bonsai should be fertilized, you must be able to understand the basic make-up of fertilizers. Most fertilizers contain three basic elements: Nitrogen (N), Phosphorous (P) and Potassium (K).
Nitrogen is an essential ingredient for leaf and stem growth. Too much nitrogen however will make the tree produce long, stringy growth. Phosphorus encourages healthy root growth and helps the growth of new buds, whilst also protecting against disease and unfavorable winter conditions. Potassium (potash) encourages the formation of flowers and fruit, and is vital in the fight against disease.
As a general rule, feed your bonsai from early spring to late summer. Use a balanced fertilizer with a fairly low nitrogen content year round, and one with as little (or no) nitrogen as possible in autumn to aid the tree (so the tree can retain its energy) through the winter.
Most commercial fertilizers contain three main nutrients plus some trace elements. One type of fertilizer usually only obtainable from bonsai nurseries has an NPK (nitrogen, phosphorous, potassium) ratio of 0:10:10. This is an autumn feed (containing no nitrogen) which will harden off the current season's growth in readiness for the winter.
Regular repotting of your bonsai to replace important nutrients, 'stale soil' and allow for new root growth is vital to your bonsai's health and growth. Generally, the trees should be repotted at a time when they are most dormant - such as late autumn to early spring, so that they are subjected to the least amount of stress possible. Young or small bonsai require repotting every two or three years, and older and larger specimens less often.
You can tell that a bonsai needs repotting if water takes a long time to drain through the soil or if the roots are crowding around the sides.
To repot, carefully lift the tree out of its current pot by tilting it to one side and trying to move it by the base of the trunk. You can not pull too hard on the trunk - so if this does not work, try tapping the pot with the side of your hand to loosen the rootball or poke a stick through the drainage holes and 'push' the rootball out. Next, using a chopstick, knitting needle, metal hook or similar, remove any moss or accent plants and carefully try to brush and untangle the roots. Start at the edge and gradually work around. Try to 'comb' and 'tug' rather than to 'pull' at the roots - for risk of damaging or tearing some very important main roots.
After this has been done - continue to shake and brush off the soil until about one third to half of the original soil has been removed from the edge and base of the rootball. It would now be a good idea to spray the roots with water to ensure that they do not dry out and so that they will not have too much soil on them when it comes time to pruning the roots. To prune the roots, use very sharp cutters. There are bonsai root pruning scissors commercially available, however you could just use a normal pair of bonsai clippers. If you have washed away most loose soil the scissors will stay sharp, but if they have to cut through soil as well as the roots - they will become blunt very quickly and require sharpening. Start by cutting the thick, old brown roots that have come close to the edge of the pot and are restricting the growth of the young 'feeder roots'. Remove a third to a half of these - being careful that you do not remove too many feeder roots in the process. Next, prune the thinner roots which hang below the depth of the pot by trimming them all into a suitable shape that the pot will accommodate. This should be a shape that fits comfortably into the pot with a 1-2 cm (1/2 to 3/4 in) space between the edges.
The demanding part of the repotting is now over - if you think that you've cut too many feeder roots off, the tree will be disadvantaged but you probably will get away with it - as new roots will grow from the cuts.
Clean the original pot thoroughly or select a new pot that is more suited to the tree and cover the drainage holes with simple wire mesh. As the plant will now be unstable in the new pot as it has nothing to anchor it - we have to make some anchors to prevent the tree from falling over from winds or from being moved. Thread some wire (doesn't need to be very thick) through the drainage holes or specially designed holes for anchoring and leave for later use. Add a thin layer of gravel to aid drainage and then a layer of soil. Moving the tree around, decide a basic position for it (usually off-center and slightly to the back of the pot) and make a small mound that it will sit on.
Now you can place your bonsai on the mound by gently nestling it in and spreading its roots out evenly through out on top of the soil. Once you are happy with the height and position of your tree (it is going to stay like that for 1-2 years), take the wires that you threaded and twist them together (usually with the aid of pliers) over the main rootball of the tree until it is held firmly (but not too tight) and will not rock. Because these wires are quite unsightly, you can remove them in a few months time once the tree has settled in.
Add more soil up to the base of the trunk - which should be just below the base of the pot. Tap the side of the pot with your hand to ensure that the soil becomes settled and that there are no gaps around the roots. Use your chopstick to incorporate the roots into the soil and to make sure that they are placed correctly.
Once the soil has been applied, you now have the option to add rocks, moss, accent plants or gravel to enhance the design. When applying moss - be careful that most of the original soil is cut off from the bottom before you plant it and that the moss (or any other plant for that matter) is not too big or vigourous for the pot or tree.
Now you can thoroughly water the tree - being aware that the soil level may settle further and that more soil may have to be added. Place the tree in a position where it will not receive extremes in temperature (i.e. not direct sun) and where it will be able to recuperate. Don't fertilise at this time - as this can burn or cause stress to the plant. You can feed in around a month though, when the roots have recovered.
Bonsai soil is much more free draining than potting soil and doesn't contain as much fertilizer as normal potting soil which is usually for plants in large pots that people want to grow really big. It is usually available at specialist bonsai nurseries, and even some normal nurseries stock it. This is probably the easiest, cheapest and least time consuming way.
Making your own soil mix isn't as hard as you think. A lot of bonsai growers make a bit of an unnecessary fuss about it. A basic bonsai soil mix to use - and one that would apply to almost all species is: one part loam, two parts sphagnum peat moss, two parts granite grit.
Pruning is necessary to maintain (or refine growth to obtain) the right shape of a bonsai and encourage new growth. Some plants naturally respond well to pruning, regardless of how intense, whilst other plants can find it hard to recover, especially when pruned at the wrong time of the year. To prune correctly you must find out the type of plant your bonsai is and research when the best times are to prune old and new season growth. Generally, new growth is pruned during the growing season to maintain the shape of the bonsai, whilst pruning of hard wood (old season growth) is done in mid-autumn.
One of the main forms of pruning for bonsai, especially evergreen coniferous bonsai such as junipers and cedars is 'finger pruning'. This involves pinching back new growth which does not come within the general shape of the bonsai or is at the top of the bonsai - helping to encourage bushy foliage and a more tree-like looking bonsai. To do this, take the growth between your thumb and forefinger whilst holding the branch with your other hand and remove with a twisting movement. This is better than trimming the growth with scissors, this leaves an unnatural look and leaves the foliage an unsightly brown.
For deciduous trees such as maples, the chinese elm and cotoneaster, scissor tip pruning is best. When trimming outward or 'overenthusiastic' growth, trim shoots back to just after the next series of leaves, but don't cut the foliage as such.
Leaf pruning (also known as defoliation) in bonsai is used for several deciduous and tropical plants such as ficus or maples to reduce leaf size, remove unsightly leaves and speed-up growth by causing two seasons' growth in one. For deciduous trees such as maples it also means that their autumn country is brighter. This is done in mid-summer, by cutting 60-90% of the leaves off the tree, only leaving a few to ensure that the tree keeps its energy. Remove leaves with fine scissors, cutting them from directly behind the leaf. In the next few weeks make sure that you keep the plant in a hospitable position and climate and supply it adequate water. Remember however, that this form of pruning is only applicable to certain types of plants.
Not all plants need wiring to achieve their desired shape or to achieve official 'bonsai' status. The Fukien Tea plant for example, can be trained quite easily without the use of wire. Contrary to what many novices may think, wiring of a bonsai is not done to keep the plant small, but rather is a temporary measure used to hold branches in a desired position in order to enhance the shape of a tree. Wire should not be left permanently on a tree and should be checked regularly.
When wiring, try to imitate the natural curves of trees in nature. Make sure that you only attempt to wire branches that are unlikely to break when pressure used to twist the wire around the branch is applied. There are two types of bonsai wire available - copper wire and aluminium wire. Although easy to obtain, less expensive and naturally a better colour than uncoloured aluminium wire (silver) - it is much harder to apply to branches, especially for beginners, and if applied incorrectly - which is easy to do, could ruin your most prized bonsai. Undoubtedly, the better wire is aluminium wire which is usually coloured to look just like copper wire and is available at any bonsai nursery. It is much more maleable than copper wire and generally has the same effect. The size of wire used depends on the size of branch you want to train and in most part should be chosen yourself - also dependent on how significantly you want to change the shape of a branch and how stubborn the species of plant is. You should purchase wire in a variety of different lengths and test it out on pruned branches from around the garden. You can always remove the wire (very carefully if on a bonsai), flatten it out and use it again. For pencil-thick sized branches use a gauge 3.5mm aluminium wire. The lowest gauge is 2.0mm.
The safest method to use when wiring is by clenching the branch with both hands (not dissimilar to the look of a clamp) and applying the wire by slowly following it around the branch - making sure it does not damage the trunk. Wire the branch first, and then worry about bending the branch (which is made possible by the wire and using the clamp method) to achieve your desired shape. Be careful of leaves or if in autumn, leaf buds. It is always best to anchor the wire so it does actually re-train the branch. This can be done by digging it into the soil and training the wire up the trunk until it reaches the desired branch, or by anchoring it to another branch. Sometimes, when it is too hard to use large gauge wire in order to train a large branch or trunk, or you don't have the right gauge of wire, you can 'double up' the wiring and wire the branch twice.
It is best to not water a day before wiring, and to keep the tree in shade for two weeks after wiring. Check every few weeks for wire cutting into the bark of the bonsai - particularly during spring and summer, or risk the danger of irrepairible scars. It can take many, many years for wire damage to grow out - depending on how serious it is. Deciduous trees are particularly susceptible to wire damage due to large growth spurts in the growing season.