A succulent plant is one that possesses tissue designed strictly for the storage of water, enabling it to go long periods without receiving any external hydration from the earth or falling rain. Plants that exist in arid, dry locales are often considered to be succulents, due to their ability to adapt and thrive in such an environment. The relationship between deserts and cacti are chief examples of plants that live as succulents in arid conditions.
While all cacti are succulents, not all succulents are cacti. The difference is that all cactus plants possess an areole, the "cottony" area from which roots, spines and flowers grow, states the University of Illinois Extension service. Not all succulents possess this areole. The majority of cacti and succulents grow during the spring and summer before moving into dormancy in the fall and winter.
Determining whether to classify a plant as succulent or nonsucculent can be a difficult proposition, indicates Mark Dimmitt, the Director of Natural History at the Arizona-Sonora Desert Museum. He says that plants like orchids are clearly succulent but not commonly recognized as such due to the fact that many succulent gardeners choose not to grow them. Plants like the giant cane milkweed, coyote gourds and rock fig are examples of other "nontraditional" succulents.
All cacti and other succulents require significant light to maintain health. The plants should be kept warm and sufficiently irrigated during their spring and summer growth cycle but dry and cool during dormancy. Succulents abhor "wet feet" and sitting in water, especially when they are dormant. This sort of environment can lead to rotting. Succulents also appreciate a temperature that ranges between 45 and 55 degrees Fahrenheit when they are dormant. During the hotter summer, they should be places in an area that receives a mix of sunshine and partial shade.