This is the single most important factor in the care of bonsai. Most bonsai die from a lack of water. A few die from too much of water. Your watering technique should be, pouring water slowly near the base of the tree until the excess water flows out the bottom of the container. As a general rule, in spring and autumn water every second day. In summer water every day and in winter water every third day. The amount of water that your bonsai needs, is dependant on 5 factors.
1. The depth and volume of soil. Your bonsai is growing in a limited shallow amount of soil with a drainage hole. A pot of 6cm in height will dry out 4 times slower than a 3 cm pot and not double as one would expect.
2. The colour of your pot. The bonsai in a dark pot will heat up faster and cause more evaporation, as opposed to a light pot, which will have less heat retention and evaporation.
3. The ambient temperature and exposure to the elements of wind, heat and humidity. The tree transpires and combined with the effects evaporation through heat and wind, will rapidly dry out the soil. You must ensure that your bonsai soil is not allowed to dry out for more than 2 days without your knowledge.
4. The bonsai species. Some species are utterly dependant on over watering, such as swamp cypress. Others do not like water and over watering may lead to root rot, such as Baobab. The amount of water depends on the species and to help gauge the quantity of water required by the bonsai, you will need to understand the origin of the trees natural environment. 5. Soil water retention. Clay type soils with fine particles will retain moisture far better than stony soils mixes. You will need to understand what the moisture retention of soil that your bonsai is grown in.
:) Hint: Place a wooden toothpick or chopstick in the soil for 5 minutes to establish the moisture content of the soil. If the toothpick is dry, water the bonsai. If the toothpick is wet, there is enough water within the soil.
CARE, HELP and INSTRUCTIONS
Bonsai is 80% horticultural principles and 20% artistic principles. So keeping you bonsai alive involves knowing how the species grows and whether it is endemic to your area. Trees that do not grow in your area are going to need extra attention and knowledge.
Being a tree, genetically, it grows best outdoors. The best location is in the garden under the shade of a tree or a shaded patio where it will receive the sunlight and not direct extended periods of the harsh afternoon sunshine. Some tree species prefer full sun while others, mainly tropical trees, may be adapted to stay indoors in a well-lit and airy room. The majority can only be brought into the home for a week or so at a time - for display purpose - before being returned to their permanent home. Others may survive for months indoors, but essentially they are being starved of their natural growing light, ultra-violet, and slowly starving, by the glass refracting Ultra Violet light.
To maintain the shape, balance and harmony of your bonsai, you are required to constantly trim off unwanted growth. This can be similarly viewed as humans needing to remove unwanted hair. In bonsai this entails the removal - pinching or cutting off - of excess shoots and leaves. Elongated branches can be cut down to 30% or the first growing leaf or bud from the trunk. Pruning will encourage new side growth, with branch movement and character, the characteristics of a good bonsai. There are tricks and methods to cutting species, so it is advisable to ask someone who knows. To understand the desired you will need to get to understand the various styles in bonsai and also the tendencies of shape that your species grows in the wild.
Due to the limited amount of soil, the tree may become pot bound within 2 to 5 years and the nutrients depleted. The nutrients in the soil need to be replaced, or your bonsai will deteriorate. In spring, gently remove the bonsai from its container. Uncoil the roots by raking out the roots. Remove about 10-20% of outer soil and roots. Cut off all dangling roots. Replace the bonsai and fill in the gaps with fresh bonsai soil mix. Dunk the container in a bowl of water to expel all trapped air. Ensure that the new soil is pressed firmly around the pot and tree. Place in a shady spot until new growth emerges.