Light

From BonsaiWIKI

Light is the trees' source of energy for growth and maintenance. Despite the term "plant food" often used for fertilizer, trees manufacture their own food from sunlight, air and water through a process called photosynthesis. Trees are adapted for growing conditions outdoors and most need several hours of direct sunshine each day. If you do bring a tree indoors, enjoy it for a day or two and then take it back outside where it can thrive.