Outdoor Bonsai
Outdoor bonsai are those trees and shrubs that are accustomed to living in subtropical, temperate, and cold climates. All conifers, such as junipers, pines, firs, spruce, etc., almost all deciduous (those that drop their leaves part of the year), and evergreens such as holly, rhododendron, camellia, etc. should spend all of their time outdoors. In cold climates, bonsai must be protected from cold winds and bitter cold temperatures by being stored in a cold frame, greenhouse or unheated garage. It is common to see junipers sold as indoor bonsai, but this is a misconception. Some books even suggest that one can bring an outdoor bonsai into the house for a day or so, but it is not recommended unless one is displaying the tree in a show, which happens infrequently.

Indoor Bonsai
A few semi-tropical and all tropical species of trees and shrubs that live in the warm climate regions of the world are suitable for indoor bonsai. Figs, aralias, sheffleras, serissas, and miniature boxwood are good candidates. It is possible to keep the trees indoors year round if they are placed by windows that give adequate light or have supplemental lighting over them. Extra lighting is highly recommended if growing indoor bonsai in places that receive less than twelve hours of daylight. One should provide as close to the trees’ original environmental qualities as one can. Indoor bonsai are sensitive to cold drafts and should never be place on top of fireplace mantels or near heat sources. All indoor bonsai will enjoy the warmest part of the summer in an outdoor placement that protects them from the hot sun.