Yucca plants grow in either a tree form or a shrub form. Tree yuccas are tall growing trees that have thick fibrous leaves on the tips of their branches. Common tree yuccas are Spanish bayonet (Yucca aloifolia) and the Joshua tree (Yucca brevifolia). Shrub yuccas, like the hairy yucca (Yucca filamentosa), are low-growing spiky plants that form rosettes of thick fibrous leaves that sprout from a central point. After both yucca plants bloom, a brown flower stalk is left behind. The flowering stalk should be removed from the plant if you do not wish for the plant to produce seed. Often, shrub yucca plants turn brown and then die after they flower, but new plants emerge around the dead rosette.
Put on leather gardening gloves and prune off the dead and dying leaves in the spring with sharp pruning shears. Avoid pulling the leaves off the plant as this causes damage.
Remove the flower stalk after it has dried, which is usually in late summer. Cut the flower stalk 3 to 4 inches above the centre of the rosette with sharp pruning shears. Remove the severed flowering stalk and discard. Pull the stalk out from the centre of the plant only if the centre is rotted and the stalk can be easily removed.
Pull the dead yucca plant out of the ground gently when you notice new plants forming around it. Use caution not to disturb the newly emerged plants.
Prune off only dead or dying leaves with pruning shears. Removing green leaves damages the tree. Wear leather gloves to protect your hands.
Cut the flower stalk panicles off the tree after a few weeks of blooming if you live in a wet area. Cut the panicles 3 to 4 inches from the centre of the leaves with sharp pruning shears. Dead flower stalks will fall off the tree leaving behind a hole where water can get into the heart of the plant and rot it out from the inside.
Cut the flowing stalks anytime if you live in a dry climate. Cut the stalk panicles 3 to 4 inches from the centre of the leaves with sharp pruning shears. It is not harmful to leave the flowering stalks on the tree if you live in an arid area that does not receive much rain.