Root pruning a Haworthia can stimulate the growth of new roots, which are more efficient at uptaking waters and nutrients. When taking a plant out of the container for caring or propagation, or receiving a new plant, it is recommended to take this chance to prune its roots, as long as the temperature is not too high.
After removing the growing medium, remove any roots which are dried, hollow or rotted. They don’t function but can just cause rotting. Fine roots can also be safely removed as they are likely to dry out while waiting for wounds to recover.
If a Haworthia has a large underground stem, trimming the stem helps reduce the risk of rotting and make room for new roots. But this will create a large wound and the plant needs more time to recover. Therefore, trimming should be done only for a mature plant that can survive during this period.
After pruning, treat the wounds properly to let plants recover sooner.