The side roots are cut out with a spade, at about six to eight inches from the trunk. At eighteen months the side roots are cut again. Then the tree is planted in a shallow flowerpot. The taproot is now cut, stopping all means of future growth. The shape if the container is carefully selected to blend in with the theme of the scene envisioned and the type of tree being cultivated.
Containers are usually of earthenware.
It will be lined with a metal net to prevent the earth from sticking to it s sides. The tree remains in it s original container for two or three years, after which it is replaced to prevent the roots from rotting. Then the twigs are pruned with scissors, and the branches are bent by wire to achieve the desired look. At regular periods, the tree is lifted out of the pot for cropping of the roots. Bonsai thrive in fresh air and so, unless in cold weather, can be left outside.