Bonsai trees should be repotted every two years and their roots pruned and manicured. Bonsai roots must be kept short and evenly distributed across the area of the pot. In younger trees, as much as two-thirds of the root can be removed at each repotting, and after repotting, plants should be kept in semi-shade and protected from hot weather until they've had a chance to acclimate.
A bonsai tree that has weathered a number of seasons can be treated differently from a young plant. Pruning and shaping from year to year isn't as extensive, and repotting, although still performed every couple of years or so, will not require a new pot. Occasional repotting to remove excess root growth invigorates the plant while helping to retain its size and keep it in its accustomed pot.
Measures can also be taken to enhance the design and personality of an established bonsai tree and deepen the illusion of age and majesty that is prized in older specimens. Weathering a tree's trunk through bleaching (Jin and Shari), and adding an assortment of quality mosses and groundcovers like Selaginella and Crassulacea to the soil to approximate forest undergrowth enhances the appearance of an established bonsai arrangement.
The elements that distinguish a remarkable bonsai tree are subtle but profound. The subject shouldn't just look like a miniature tree; it should retain the presence and naturalness that proclaims that it's a living thing. It should carry with it an echo of its natural environment, and give the viewer an immediate sense of recognition, wonder and delight.
Visit the next section for links to more bonsai information and other great articles.