Senecio rowleyanus ‘String of Pearls’

This plant will want water around every two to five weeks. Let the soil totally dry out, but don't let it go bone dry and then sit around for a month or so; once they are totally dried out, they want water! Remember that the top of the soil may feel dry, while residual water remains deeper in the pot. Since water is heavy, a light potted plant often indicates it's time to water, especially with smaller pots. It's also a good idea to keep an eye on the plant: If leaves are shriveling, or even dropping off, you've probably gone too long without watering.

You can think of each leaf as a tiny water tank; when the plant encounters drought it goes to these reserve water sources and uses them up.