Bonsai is an art of dwarfing trees and perennial shrubs. A bonsai is not just a dwarfed plant, but it should depict all the characteristics of an age-old tree in its full glory. It is not at all difficult to dwarf a tree or a shrub. But, skill is needed in making it a mini replica of a giant tree with all its glory and ruggedness,
Choosing plants : Any of local, perennial trees or shrubs, preferably with tiny or smaller leaves can be chosen. These days a number of exotic foreign plants too are available for bonsai. The chosen plant should be amenable to constant pruning. Gulmohar and Mango trees are not very suitable, as they do not like regular pruning. Imli, Vilayati Imli (Manila tamarind), Indian coral tree, Bottle brush tree, Parkinsonia, Casuarina, Persian lilac, Sandpaper tree, varieties of Ficus, Guaiacum and Baobab tree some of the trees which are suitable for bonsai. Malpighia, Kamini, Serissa, Lantana, Galphimia, Duranta, Calliandra, Bougainvillea, Carmona, Ravenia, Schefflers, Aralia, Portulacaria (Jade plants) and Adenium are some of the suitable shrubs.
Containers : Earthen or ceramic containers are most useful. The pot should have its mouth larger than its base. Containers with constricted mouths should not be used, as changing soil and root pruning in these pots is difficult. Drainage holes should be large to enable fast drainage of excess water. Except for cascade style, where a tall pot is used, all the pots chosen should be shallow. The size and the shape of the pot should be suitable for the style one chooses. The chosen pot should not be too big or too small for the bonsai plant.
Soil Mixture : Really speaking, it is immaterial whether one uses a graded mixture of soils or no. Any good garden soil with equal proportion of farmyard manure is good enough for a bonsai. Remember that bonsai are just like any other normal plants, except for their size. If a small quantity of sand, vermiculite, rice husk or brick granules are used in the soil mixture, it will remain porous for longer periods. The porosity in soil aerates the soil; thus promoting healthy root growth and also facilitates faster drainage. Also, if soil remains friable, it will be easier to change the soil at the time of root pruning and repotting. This will prevent the excessive damage to hair roots, which are primarily responsible for absorption of water and nutrients. The soil mixture should be moistened before use. Moist soil can easily fill the crevices between the roots. The wet soil forms lumps and leave large air pockets, which will harm the roots.
Implements : Secateurs, small poker for loosening soil, pliers or a wire cutter, watering can with a fine sprinkler and a spray pump (optional).
Materials : Good garden soil, farmyard manure, nylon netting, moss and copper wires of 20, 18 and 16 gauge. (Sand / vermiculite / rice husk optional).
How to get plants : Visit the nurseries to find a good source of healthy plants. Plants bought from a nursery will save you the time, as they will be already grown up. Alternately, one may grow the plants from seeds, by cuttings, or by layering / grafting / budding.
Useful hints : If you buy a plant from a nursery and if the plant is too big to be accommodated in the chosen bonsai pot, then first do partial pruning of branches and roots. Repot the plant in a slightly smaller pot. Allow it to stabilize. After this, branch and root pruning can be done again for repotting in a even smaller pot. This process must be followed till the plant can be accommodated in the chosen small pot. Sudden, severe pruning of the roots and branches could do a lot of damage to the plant.
Before you buy a plant think of the style you want to do. Accordingly, choose a plant most suitable for the style. For instance, if twin trunk style is desired, do not buy a plant with a single trunk and then wait for another trunk to grow. Similarly. For a wind swept style buy a plant with already tilted trunk.
Pruning and Pinching : Pruning of branches is done either to shorten a branch or to eliminate it. Pinching is done to encourage side shoots to grow and thus to make it grow dense. Branch pruning and pinching alone is responsible mainly in dwarfing of the plant. Remember that this pruning and pinching is a regular process. Unless this is followed regularly, plant will revert back to its bigger size. Of course, in the initial stages pruning and pinching is needed to be done more often, but, as the bonsai matures, it suffices only to pinch it to maintain its size.
Root Pruning : A potted plant can be dwarfed without pruning its roots. As explained earlier, the branch trimming and pinching only keep it dwarf. If so, one may ask a question, “Then why are the roots pruned?” The reason for it is only aesthetics. A beautiful bonsai in a large over-sized pot will look very disproportionate. Moreover, in a shallow and smaller pot a bonsai will show off its full splendour more artistically. So, to enable one to accommodate a plant in a smaller pot, it becomes necessary to prune some of the roots. If roots are not pruned then there will be no place for the soil to go in to the pot. In a plant there are two types of roots – hair roots and matured roots. Hair roots are mainly capable of water and mineral absorption. The matured roots give plants support to stand firmly. Since bonsai plants are small in size and comparatively sheltered, some of the matured roots can be eliminated. Also removal of about 1/3 rd. mass of the hair roots will do no harm to a plant. By severely damaging the hair roots, the plant will be starved of water and thus will wilt. Some of the matures roots near the soil surface should be exposed to air; keeping their growing tips below the soil. These roots impart a bonsai with a matured look. Roots need not be trimmed until the plants seems to be getting root-bound.
Shaping : To bend and twist the branches to a desired shape, following processes are followed. Tying, wiring and tilting. Tying is a process in which branches are tied down or up and secured to a support to get the desired effect. In wiring, soft copper or aluminium wires are wound around a stem in a helical manner. (like a spring.) Thicker the branch, thicker will be the wire used. Normally 20, 18 and 16 gauge copper wire suffice. (note : larger the number of the gauge thinner will be the wire; i.e. 20 gauge wire will be thinner than 18 gauge wire.) After wires are wound, the branches could be bent to a desired form. Certain plants like bougainvillea, which have hard and brittle branches, can not be bent severely at one go. The process of bending them should be done gradually. After the branch has acquired the desired shape (After a few months) the wires are removed. If the wires are left on the branch for very long, they will leave spring-like scar on the branches. By tilting or by inverting the pots for a prolonged period, the branches of a plant can be made to bend in natural curves. Tilting method is suitable mostly for flexible branched plants like aralia.