A bonsai is pot-bound when its roots have filled the container and there is no more room for them to grow. This can cause problems for the health and appearance of the bonsai, as it may become stressed, dehydrated, or root-bound. Pot-bound bonsai also require more frequent watering and fertilizing, as they have less soil to retain moisture and nutrients. To prevent or remedy this situation, the bonsai should be repotted regularly, usually every one to three years depending on the species and the size of the pot. Repotting involves removing some of the old soil and roots, and placing the bonsai in a slightly larger container with fresh soil. This will allow the bonsai to continue growing and developing in a healthy way.