Light

Plants cannot live without light. If we lived only in darkness, all of us would get sick, because only light can transform air, water, and nutrition into growth and life. When selecting places for your indoor bonsai, don't forget that in almost all cases the summer and winter months are equally long, and the light during the day is more intense in the plants' native-habitat than it is in temperate zones. Also, remember that most homes have only a few places-particularly during the winter months-where the amount of daylight available to bonsai is sufficient. The ideal spot for bonsai would be a place by the window where light is not obstructed by large trees, high walls, or a roof overhang. Even 3 feet (1 m) away from a window, the degree of luminosity is greatly diminished, although this is not noticed by our eyes. That might already be too dark for a bonsai. If that is the case, you will notice that your bonsai becomes straggly and tall. If you notice that your bonsai doesn't seem to receive sufficient light on one side, turn bonsai tree around once a month.

Light means sunlight, but-particularly during the height of the summer season-not direct exposure to sun. Especially during the middle of the day, this might be too much for even the most sun-hungry plant. Protect bonsai by adjusting window blinds, or use a light-transmitting shade. The degree of brightness is measured with a luxometer - a very simple and inexpensive instrument that is similar to the light meter used for taking photographs. The more artificial light your bonsai needs, the longer the artificial lights need to be on-perhaps from 12 to 16 hours. Accuracy in terms of the length of time artificial lights are on is very important for your plant. You need to turn them on and off at the same times each day. This can easily be accomplished with the help of a timer.

Providing sufficient light is a particular problem during the winter months in temperate regions, even if the bonsai is kept on a windowsill. The days are simply too short. Lengthen those days with the help of artificial light: in the morning before sunrise and in the evening after sundown. During October and March, you might need approximately one hour; during November and February, two hours; and during December and January, about three hours. This will vary depending on where you live.

Regular incandescent light bulbs are not suitable light sources for your bonsai. Their light does not correspond to that provided by normal daylight; your bonsai may even suffer damage from the excessive heat that they produce.

It's best to use artificial light that approximates sunlight in giving a wide spectrum of colors of light. Choose fluorescent lights that have daylight and warm light ranges. This gives a better result than plant lights that are in the violet range only. Fluorescent lights, like those used to provide light for fish tanks, are good sources of artificial light. Depending on the light source used, your lights, generally speaking, should be suspended about 10 to 32 inches (25 to 81 cm) above bonsai.