Normal radial root pattern on Casuarina in Hawaii

Close up of normal radially spreading roots

Normally roots grow radially outward from the trunk unless diverted by some obstacle; if they meet an obsturciton roots will try to grow over or around the obstacle.

When trees are grown in pots their root growth is eventually restricted by the edge of the pot and then the root is deflected and grows around the edge of the container. If kept in the pot for too long a time the roots will continue to circle the pot creating a rather disconcering root pattern.

In bonsai we most often strive to produce the illusion of a tree growing out in the wild and tirelessly remove any evidence of artificial or man-made appearance which detracts from this feeling. Repotting at appropriate intervals as well as trimming back and re-orienting non-radial roots will keep the root pattern morenatual and visually interesting.

With Ficus the offending roots can often just be cut off, leaving a radial root pattern. With someFicus species the root can be used to start a new plant.