Despite its name, the ponytail palm (Beaucarnea recurvate) is not actually a palm tree at all. It is similar enough in appearance, however, to please gardeners who live in areas where genuine palm trees cannot thrive. Hardy to U.S. Department of Agriculture growing zones 10 and 11, the extremely low-maintenance ponytail palm can be grown potted in a controlled temperature environment nearly anywhere. If you wish to keep your plant under such conditions, though, you will need to control its growth by trimming the roots regularly and repotting the plant when necessary.
Watch your ponytail palm carefully to know the proper time to repot the plant. When you notice some swelling in the trunk at the base, just above the soil line, it is time to relocate the ponytail palm to a larger pot.
Mist the soil around the palm with water until it is just moistened. Slide one hand beneath the bottom of a smaller pot, or turn a larger pot carefully on its side and wrap the fingers of your other hand around the trunk. Tap the bottom of the pot gently and then wiggle it until you feel the root system loosen.
Slide the ponytail palm completely from the pot and set the container aside. While holding the palm in place, trim each visible root to no more than 2 inches long using sharp hand-held pruning shears.
Pass a pronged hand cultivator over the entire root ball to loosen the system. Trim any newly-revealed roots that are longer than 2 inches, and remove any damaged or poorly-formed roots at their base. Repot your ponytail palm as desired.