Ponytail palm (Beaucarnea recurvata syn. Nolina recurvata), also known as elephant foot tree, is not a true palm but rather a member of the asparagus family, Asparagaceae. Native to Mexico, in desert, shrubland or dry forest locations, this plant grows 20 - 40 feet or more in its natural environment. It has been assessed as critically endangered due to habitat destruction and species harvesting for the high demand of the ornamental plant market.
Ponytail palm has long, curving, strap-like leaves that give it the ponytail name. There are other Beaucarnea species also sold as ponytail palm houseplants. Beaucarnea stricta, for instance, is similar with narrower, straighter leaves and trunk than Beaucarnea recurvata. Beaucarnea guatemalensis often has a red tinge to new leaf growth and at the leaf base. These plants can be grown outdoors only in the hottest, driest parts of the United States. In the northeast, they are kept as a slow growing houseplant that can nonetheless reach six to eight feet tall after decades of growth in the most beneficial conditions.
Ponytail palm is easy to care for as long as overwatering is avoided. The large and interesting base of the stem (caudex) serves as water storage. Caudiciform plants like this one are typically adapted to arid native environments. From November through February, this plant needs a winter rest with dryer growing conditions that simulate the conditions of its natural habitat.
Ponytail palm needs strong light exposure. In the northeastern United States, it will be healthiest in a south-facing window with direct or indirect light but can adapt to a bright room with southern light or an east- or west-facing window. Consider using artificial light to supplement if your light source is not bright. Your plant will benefit from being turned weekly so that all sides receive equal light. In adequate light, the leaves will grow slowly and new leaves may sprout.
Water your plant in the morning with tepid water to make all the potting mixture just moist, then allow it to drain completely through the drain hole before removing the run-off water. Take care not to water into the foliage of the plant where it can settle on the caudex and initiate disease. The soil should be nearly dry before you water it again. If in doubt, wait! A simple moisture meter can help you to determine soil moisture deep in the container. If the soil is allowed to stay too wet, it can kill the plant.
Keeping your plant in a container that allows it to drain and then removing the water is essential to its health. A pot with a removable run-off dish is best; incorporated run off dishes do not release water as well.
In fall through winter, reduce water a bit but don't let the roots dry too long. This plant originates in seasonally dry environments and this water reduction imitates the pattern of rain it would receive there.
No need to mist! Your plant prefers low humidity.
Ponytail palm is from a dry and hot habitat and likes warm household temperatures. Keep it in a warm, dry location with temperatures in a 65 to 75ºF range and no door, vent or window drafts. If temperatures dip into the low 50's, it can kill the plant. It can withstand very high temperatures but is easier to care for with less fluctuation.
Feed the plant lightly with a cactus fertilizer, or balanced houseplant fertilizer, every other month, in spring and summer only. Overfertilizing can lead to soft, weak growth.
Re-pot your plant every two years in the spring only if the base of the stem encroaches upon the edge of the pot. Generally, a clean pot of the next size up with fresh soil is fine as the plant grows slowly. Moving to too large a pot risks root and stem rot.
Handle the plant carefully as you move it so as not to damage the roots. Keep the plant in a pot with a drain hole and a run-off dish that is not attached to the container. Do not set the plant any more deeply into the potting soil than it has been growing in its old pot; burying the stem will lead to rot.
Ponytail palm likes a gritty soil and relatively small pot with excellent drainage. A cactus potting medium with no added fertilizer or a mix of three parts grit or sand (for drainage) with one part potting soil (for organic material) and a small amount of coir or shredded bark (for texture) make suitable soils. Plants that are potted in the wrong mixture will initially do well but may later suffer from root rot associated with excess water retention in the soil. A thin spread of grit or small pebbles as the top layer of the potting mixture is helpful to prevent stem and leaf contact with wet soil.
This plant is reliably reproduced by seeds which can be difficult to source. Growth is slow. Potting up the offsets is possible but has a variable success rate. If you would like to try to propagate the offsets spring is the best time. Allow them to grow for some time on the parent plant (6 inches tall) for greater vigor. Cut the offset away with a sterile cutting tool, allow the cutting to callous for several days and trim off some bottom leaves so that there is more of a trunk to the little plant. Brush the bottom 1/3rd of the stem with rooting hormone and insert that part into a gritty potting mixture. Water only very lightly until roots develop. You can also simply remove these offsets from the plant if you prefer a single trunk.
Eventually, a plant may become too tall and leggy for the space or lose so many leaves that it's time to cut it back. Success will depend to some extent on the condition of the plant and is not a sure thing, so reserve this drastic pruning for a situation that demands a severe approach. Use a sterile cutting tool to reduce the height of the stem in spring when the plant is entering a growth phase and will respond most vigorously. If all goes well, new growth will appear in several weeks just below where you make your cut. Take care not to let the wound on the stem top get wet while it heals to avoid infection.
A wrinkled and soft stem base may indicate bacterial or fungal rot to roots or stem. This can happen quite easily if the plant is overwatered, the container does not have adequate drainage, the run-off dish is not emptied after watering, or the wrong soil is used. If more than a slight soft and wrinkled patch, the plant is unlikely to recover. For smaller patches that do not extend to the roots, it is possible to excise the rotten portion of the stem with a sterile cutting tool.
A wrinkled stem is typical of many plants, particularly as they age. If it is not typical of your plant, investigate further for soft or mushy texture, feeling under the soil level at the base of the stem, and review watering frequency.
Dust collects easily on the plant leaves. Wiping them clean a few times a year will benefit your plant as it improves photosynthesis.
Dry leaf tips are very common. This can occur if watering is irregular (overwatering, underwatering or a bit of both), light levels are too low, temperature has dropped below an acceptable threshold, the plant is too near a heat or air conditioning vent, fertilizer salts are building up or if the water has high mineral content. It is less likely to be a result of low humidity. You can snip off the brown areas if you like. Correct growing conditions to improve appearance.
Oldest leaves turn brown. If entire leaves turn brown and dry in very limited numbers, this is a natural occurrence. You can gently remove the leaves.
Leaves discolor when exposed to cold temperatures. A plant that has been shipped to your home may have encountered stressful temperatures. Leaves can also burn if moved outdoors to direct sunlight without a period of transition.
A stump at the base of your tree's leaves is evidence of the technique used to stimulate palm-like growth. The stem is cut and multiple stems sprout from around the cut to create the "ponytail". If not cut in this manner, a ponytail palm will have a single set of leaves at the top of the stem.
Red hue at the base of leaves or on new leaves indicate your plant may be Beaucarnea guatemalensis rather than Beaucarnea recurvata. The plant may take some time to reveal its identity because it grows so slowly. Leaves can also darken to a red-brown hue in strong sunlight.
The Complete Houseplant Survival Manual by 
