> Keep in mind that NO tree will be at its best indoors. All trees are native outdoors somewhere on the planet.

> If your winters are harsh, certain trees must be kept indoors out of necessity. Requirements for various trees will vary a lot. You need to join a club or read reference books to find out what your individual tree needs.

> Five basic elements influence a tree's growth and health: water, temperature, relative humidity, light intensity and air circulation. Lack of a necessary element will inhibit growth and possibly encourage pests or disease.

> Some trees will survive in average household temperatures with some added humidity and supplemental lighting.

> Others require a cooler environment that can be provided in an attic or unheated room.

> Some trees need to have good air circulation.

> Many enthusiasts (who must grow tropicals and subtropicals indoors in the winter) put their trees outside in warm weather to give them a chance to thrive.

> One of the easier trees to cultivate indoors is the ficus. Ficus come in several varieties suitable for bonsai including weeping (benjamina), mistletoe (diversifolia) and creeping (pumila).

> Scheffleras and jades (either crassula or portulacaria) are relatively easy to maintain.

> Among trees that will grow indoors and may flower are snow rose (serissa), brush cherry (eugenia), natal plum (carissa), dwarf geranium (pelargonium), Chinese sweet plum (sageretia), fukien tea (ehretia) and fuchsia. These take more than average care and probably should not be attempted by a beginner.

> Many plants that are treated as houseplants can be trained as bonsai. These include some dracaenas, false aralia (dizygotheca), ming aralia (polyscias) and china doll (radermachera).