There is nothing particularly hard about the growing and care of bonsai trees, but they do require constant care in order to thrive.
Bonsais require the same three ingredients essential to all plants - soil, water and light. The trick in providing the proper care of bonsai tree is ensuring they get just the right amount of these crucial elements. While it's not difficult it does require a little specialist knowledge and without the proper application of that knowledge your bonsai will probably very quickly die.
Many people new to the care of bonsai trees assume they should tend to it in the same manner as any other potted plant. Despite the fact your bonsai is potted, it is not, in any true sense of the word, a pot plant. It is a miniaturized tree and as such thrives best in the same conditions as a normal tree of the same variety. Most bonsai therefore prefer to be outdoors, however it does depend on where you live and what kind of climate your tree is suited to.
In order to provide the best care of bonsai trees you need to do some research to determine the conditions that best suit your particular variety of tree. If you live in an area where it snows during winter, leaving a tree outside is fine, and probably best, if your tree has been adapted by nature to those conditions [such as a fir or juniper]. You may find your bonsai prefers to be outdoors in winter, rather than cosseted inside. However if your bonsai is a more tropical plant, such as a bougainvillea, leaving it outside in even a mild frost could prove fatal. Check exactly what conditions are native to your particular tree and find a position which produces the closest match.
Correct watering is also vital to ensuring your tree stays alive. Because the roots of your bonsai have been trimmed there is less mass to undertake the task of taking up water to feed the tree, therefore frequent watering is a must. You may not need to water every day, but you should make a daily check of the moisture content of the soil in your bonsai pot. If the soil gets too dry your tree will begin to lose leaves and, if left completely dry for several days, it will quickly begin to die. However keeping the soil too wet can encourage fungal growth and root rot, also leading to the demise of your bonsai.
One easy way to check the moisture level is to poke a small stick, like a toothpick or chop stick, into the soil. It may be dry on the surface of the pot but still contain moisture around the roots. You may find you need to water your tree several times a day during a hot summer but leave it without for days, weeks or possibly even months during the winter.
It is also a good idea to occasionally ensure the roots get a good soaking by popping the bonsai pot in a tray of water. Do not, however leave it in too long and also ensure your pot has plenty of drainage holes to allow excess water to run out.
Finding the right balance can be a matter of trial and error but one handy little trick is to get used to judging the weight of your tree, pot and soil. About one quarter of the weight should be water, so if your pot is feeling lighter than normal it is probably time to give it a drink.
You can use any good quality potting soil
Try to ensure your bonsai is shaded from the sun during the hottest part of the day. But again, each variety of tree prefers slightly different conditions and you should try to emulate its natural habitat as much as possible. Because plants naturally grow towards the light, it is a good idea to turn your plant regularly so that all sides get an equal amount.
The care of bonsai trees can be likened to the care of a small child. Like babies they require constant and tender loving care. It can be very costly learning through your mistakes. It is easier on the pocket and also less frustrating to learn the proper techniques before attempting the care of bonsai trees.