Trim flower stalks off at ground level with a sharp pair of loppers or shears to clean up the plant. You can do this after the plant finishes flowering in the late spring or summer, or in the early spring the following year. Be aware, however, the seed pods yuccas form after flowering can add interest to the garden if desired.
Prune away dead foliage at the ground with a sharp knife to improve the plant's appearance. If the yucca is a tree, cut the dead foliage as close to the trunk as possible. Do this type of pruning every year in the early spring before the yuccas begin the next growing season.
Trim off the ends of yucca foliage to remove the razor-sharp tips with a pair of garden clippers, if desired. This may be necessary for low-growing yuccas in landscapes where children and animals play.