People who move to Arizona start buying and planting cactuses around their house or in pots on their patios. They often kill them though because they water them too much. Or, they think the cactus never needs water and they fail to water them in the heat of the summer months, when it is amazing that any plant survives the 110 degree heat. Generally, cacti need watering about once every two weeks in the summer but the more established the cactus is, the less hand-watering is necessary. Monsoons provide much-needed nutrients and water to cactus. I tend to err on the side of overwatering my cactus, but I do try to mimic actual rain by gently sprinkling a few drops on the cactus starting at the top of the cactus, not at the base of the cactus. The structure of the cactus is generally designed to catch raindrops as cactus have very shallow roots.