Keep the saguaro cactus in a large container. Make sure it is planted in a soil mixture that is one part potting soil, one part sand and one part pumice or gravel. The hearty roots of the saguaro cactus thrive best in coarse soil.
Poke drainage holes in the container holding the saguaro cactus plant. Saguaro cacti thrive in dry conditions, making proper drainage essential. For a twelve-inch container, poke at least six holes, each one-eighth of an inch in diameter, throughout the base of the container.
Place the saguaro cactus in direct sunlight. Pay attention to nighttime temperatures, and move the cactus indoors when temperatures are at or near freezing.
Water the saguaro cactus every day during hot, summer months by saturating the soil until you notice water coming out of the drainage holes. Reduce watering to once per week during colder, winter months.