The ponytail plant, or Nolina recurvata, is a member of the agave family. This exotic and undemanding house plant is a desert native, easily killed by improper watering habits. Desert plants typically develop deep root systems for water storage to survive long periods of drought. In addition, this unique, slow-growing plant stores water in its bulbous base. It's best not to water your ponytail if you aren't quite sure whether it needs it or not.
Set the ponytail palm plant into the sink and water it thoroughly. Add water to the pot a little at a time, allowing it to soak into the soil before giving it any more. Repeat until water either no longer soaks quickly into the soil or begins to run out of the pot's drain holes. Leave the plant in the sink for several hours to give it a chance to drain very well. It will be at least a week before watering will be needed again.
Poke your finger into the soil. If the top 1 to 1-1/2 inch feels dry to your touch, it's time to water the ponytail plant. If you're doubtful, don't water. Don't be alarmed if two to four weeks pass before it needs to be watered again.
Monitor the ponytail's leaves carefully. If new growth appears light in color or rot appears on the stem or roots, you're over-watering. This will progress and cause a fatal rotting condition. If foliage feels dry or turns brown, or if the base begins to shrivel, the ponytail isn't getting enough water.