Most indoor bonsai are broad-leaved tropical and subtropical trees. Like Ficus (fig), many are also grown as houseplants, so are fairly easy to recognize. A few indoor species, such as Podocarpus and Juniperus procumbcns, are coniferous and could be confused with hardy outdoor bonsai Outdoor bonsai, on the other hand, are hardy species that grow naturally outside. Broad-leaved species, such as Acer (maple) and Crataegus (hawthorn), and conifers, such as Pinus (pine) and Juniperus. (juniper), are not difficult to identify as outdoor plants.

Many bonsai growers now use the Japanese soil Akadama, which is a clay granule that is free draining but moisture retentive. It can be mixed with humus and sand to suit local growing conditions. A good compost consists of peat, sharp sand and loam. The proportions of the three basic ingredients vary, depending on the genera. Pinus (pine) and Juniperus (juniper) need two parts sharp sand, one part peat and one part loam. Fruiting and flowering trees usually prefer a , loamier soil, with up to 50 per cent loam. Include as much as 50-75 per Cent Peat (or peat substitute) for indoor bonsai.