Find the tree you want to collect. This often requires exploring parts of the outdoors with harsh environments. Good bonsai are often old trees which have been stunted by poor growing conditions and are interesting or artful to look at. Be sure to obtain permission from the landowner to collect trees before proceeding.
Prepare the tree to be dug up. This involves pruning it back, and is best done during midsummer. Using the spade shovel, cut the roots that extend too far away from the tree which will be impossible to dig up with the tree. Do not cut roots inside of the drip line formed by the outer edge of the tree's foliage. Consider trimming back the foliage to reduce the tree’s water needs. Do not remove more than a third of the roots or foliage at one time.
Dig up the tree. Do this in early spring, before the tree has budded, the year after pruning. Collect as much of the root ball and the dirt surrounding it as possible.
Nurse the tree through the shock of transplanting. It often takes bonsai trees two to five years to recover their vitality after transplanting. During the first year, the tree may require daily attention and care. This means regular watering and feeding and, depending on the type of tree, may include adjustment of climate factors such as light, temperature, humidity or airflow. Do not begin shaping or training the bonsai until it has had at least one good growing season.