The physiologies of bonsai trees are that of any other trees. They are in essence outdoor organisms that have evolved to be accustomed to the raw elements of nature. As bonsai cultivators, we do our best to replicate the natural conditions that are best suited for a particular bonsai tree.
To put it simply, bonsai trees grow best in the outdoors as they are exposed to their natural environment. Nevertheless, there are many bonsai enthusiasts who have refined the skill of keeping bonsai indoors.
Generally speaking, there are no species of trees that are known to flourish better indoors than outdoors. Unless you are able to replicate its natural conditions indoors, most bonsai trees will eventually die when kept indoors.
If you plan to plant your bonsais indoors, you will have to select the right breed of plant based on the tree species and the weather condition in your region. If you live in an area with extreme weather conditions (such as scorching heat and icy cold nights), it may be best to plant your bonsais indoors are most bonsai tree species are from tropical and temperate climates.
For those who have just got started in this hobby, it is best to select a tropical tree species if they are planning to plant it indoors. Tropical bonsai trees are relatively easy to maintain and will grow well indoors given the right condition.
Regardless of the type of bonsai tree that you are choosing, light and temperature are the most important elements for indoor planting.
When planted indoors, the bonsai should be placed near a window or in area that is exposed to strong natural or artificial lighting. Most tropical and temperate bonsai trees cannot tolerate temperatures below 40 degrees Fahrenheit. Ensure that the room is maintained at a consistent temperature, as large fluctuations would unduly stress the trees.
Trees that originate from subtropical or temperate climates require a little more care when kept indoors. In the wild, such trees will go through a dormant state during winter. During this period, trees like the Chinese Elm and Japanese Maple would shed their leaves and enter into a state of dormancy. When deprived of this state (by providing strong lighting and high temperatures all year long), these tree varieties will eventually die.
To provide these subtropical species with the necessary dormancy period, the plants should be exposed to temperatures below 40 degrees F for about six to eight weeks every year. The exact temperature and timing for these periods varies according to the tree species that you are planting.
In short, planting bonsai indoors is much more challenging compared to planting bonsai in the outdoors. For newcomers to bonsai cultivation, it is best to start by planting bonsai outdoors to learn more about the natural behaviors of the trees before you attempt to plant them indoors.