Underwatering

What's happening

Ponytail Palm coasts a long time on the water stored in its caudex, but if it goes months bone dry the base wrinkles and softens inward, the oldest leaves yellow and crisp, and growth stalls. This is far less common than overwatering, but it does happen with neglected plants in small pots.

How to fix it

Water thoroughly until it runs from the drainage holes, then let the soil dry out fully before watering again. If the soil is so dry it repels water, bottom-water: set the pot in a few inches of water for 20–30 minutes, then drain completely. The swollen base should plump back up over the following days. Settle into watering every 2–4 weeks once the soil is dry, more often in summer and less in winter.

This is general guidance based on common symptoms; individual plants vary.