Yuccas (Yucca spp.) are native to the arid landscapes of North and Central America and nearby West Indies. Their long, pointy leaves and upright flower spikes make attractive additions to gardens with dry soils and abundant sunlight. Yuccas may be easily confused with century plants (Agave spp.), which die after flowering. Yuccas grow slowly and develop a trunklike stem, whereas century plants lack stems and remain a rosette of leaves. Think twice about cutting the top off a yucca plant, as it can create a rather ugly plant for a few years.
About 40 species of yucca exist, growing as perennial evergreen shrubs or small trees, depending on how tall of a stem they develop after decades of slow growth. When young, the rosette of leaves emanate from a central pointy growing point or tip. As new leaves emerge and orient horizontally, the oldest and lowermost leaves eventually die and wither away. The constant appearance of new leaves eventually creates a trunklike stem. Very old plants may sprout suckering clone plants from their roots. New growth on yuccas only rises from the growing tip.
Pruning off the top growing tip on a yucca effectively halts the plant growth and addition of height. No new leaves emerge from the top of the plant and the leaves present will continue to photosynthesize light but eventually die and drop off. New leaves will occur only if dormant buds under the pruning wound sprout and become the new upright stem leaders. Cutting the top off a yucca also creates a stark, ugly plant that resembles a decapitated body with abrupt architectural silhouette.
The most common pruning maintenance conducted on yucca plants is removal of spent flower spikes, a task referred to as deadheading. Once the flower spikes produce any seeded fruits and they drop away, the dried barren stalk persists for several months. To improve the appearance of the yucca, cut off the old flower stalk at the base, as close as possible to its origin near the growing tip. Do not accidentally cut or damage the growing tip, otherwise new leaves may not grow to keep the yucca looking uniform and attractive.
If a yucca plant is getting too tall or lanky in habit, it may be better to completely cut away the tall stem and allow the small plantlets, also called pups, at the base to replace it and create a bushy, more attractive specimen. Cutting off a lone yucca stalk to the ground may not result in new pups, but it usually does on plants with strong root systems in a few months. Food made in the plant leaves fuel the sprouting of plantlets at the base of older yucca plants.