Water the plant when the top one inch (2.5 cm.) of soil is dry. Allow the water to drain out of the pot and remove any excess from the saucer.During fall and winter, water lightly only every three to four weeks.
For instance, the mammillaria cacti species and other small cactus species can survive without any problems during the whole winter season without water. This isapproximately four monthswithout water, but they must be stored near-freezing temperatures to a couple of degrees up during the summer season.