Grow rattail cactus in a location with temperatures ranging from 50 to 75 degrees Fahrenheit during the growing season and no less than 41 degrees Fahrenheit through the winter.
Keep the plant in locations with full sun in the morning, when possible. Heat from direct sunlight, especially during the afternoon, can damage the rattail cactus.
Water the cactus until water drains out of the bottom of the pot. Empty the drainage tray after watering to ensure the plant doesn't stand in water. Wait until the soil is barely damp, then water again throughout the growing season. Allow the soil to slightly dry in the winter while the plant naturally goes dormant.
Fertilize the plant with a water-soluble cacti or standard type fertilizer as directed on the packaging every year in spring. Water the plant before applying the fertilizer.
Repot the rattail cactus every three years into a pot one size larger. Use a cacti-type soil and always wear thick leather gloves to protect your hands while handling this thorny plant.