Most bonsai trees sold at garden centers and nurseries are of
excellent quality, but there are a few points to bear in mind when buying a new plant. Age and shape of the tree; General health; Soil should be damp but not soggy, unless it has just been watered; Leaves should look bright and healthy, not burnt around the edges or spotty. If buying a deciduous tree in winter, last year's growth should be smooth and plump, with no sign of bark wrinkling; The tree should be steady in its container, which should have at least one drainage
hole. A white fungus in and around the drainage hole is natural and harmless
Purchasing A Tree
When buying a tree from a store during the summer, be sure to give it at least 2 weeks outside, avoiding heavy rain and high winds before displaying it indoors. If purchasing in winter, however, do not allow it to be exposed to frost for the rest of the season, as it will probably have begun to shoot. This is most important with deciduous trees, and while varieties of junipers are very hardy it is as well not to take any chances.
Most bonsai are hardy trees and shrubs whose natural habitat is out in the open. They are not permanent houseplants; and even semi-tropical trees should be placed outside when weather permits. During the summer the plant must be able to carry out the process of photosynthesis, and during winter it is resting and building up its strength for the coming spring. Too long in a warm room will persuade it that spring has arrived early and it will start budding. If this happens more than once, the tree will simply die of exhaustion.
Sunlight
Sunlight, especially the ultra-violet ray, affects the growth of
trees. Therefore, except in special cases such as immediately
after repotting, extensive trimming, etc, bonsai should be
placed in a sunny location. Bright light will also work well but
the tree should not be placed more than 12" away from the direct
light source.