An important technique in ensuring the success of you bonsai tree is watering. Even though bonsai watering is relatively easy, there are a number of factors that determine how often this needs to be done. Some of these factors include the climate you live in, the species and size of the tree, how deep or shallow the pot is, even the medium used to plant your tree in is important to consider. Once a tree is living in a pot, its root system is confined and therefore it will require more care then its ground living cousins.
If you water too little you risk your tree drying out and dying. If you water too much, well then there is the risk of root rot, which can also harm the tree. If the tree is planted in a free draining medium then the risk of root rot goes down significantly.
The best rule of thumb is to water your tree when the medium has dried a little. It should never dry out completely nor should it always be wet. Over time you will be able to tell just by sight however to begin you can check by touching the soil medium, under the surface layer with your fingers. During the summer depending on how hot it is you may need to water your tree more then once a day. In the winter you may only need to water it once a week. A good safe guard is to check your trees daily.
It is also a great idea to do some research on the tree species you are dealing with. Many species will also have their own preferences which could include letting them dry a bit more in between watering.
How to water
When it comes time to water you tree, it is best to use either a hose attachment with a fine rose or a watering can. Water from the top down, wetting the whole tree in the process. Give the tree a thorough soaking ensuring that the whole root ball gets a share of the water. Keep going until you see water drain from the bottom of the pot. We water the whole tree because the foliage absorbs moisture, we get rid of any dirt on the tree and also most insects and pests do not like being wet. The fine rose ensures that we don’t wash away the top layer of soil.