Succulents (including cacti) evolved to withstand periods of dryness -- the Atacama desert of South America's west coast is virtually without rain while the Peruvian Desert to the north and the Patagonian Desert to the south are also quite parched. Portions of the Great Basin, the Mojave Desert, the Sonoran Desert and the Chihuahuan Desert, all within the southern portion of North America, receive their pittance of rainfall during specific times of the year and are left bone-dry for months in a row. Most of the world's cacti grow within these bounds. The vast majority of the Middle East, much of Australia, and a substantial portion of Asia are composed of arid and semi-arid deserts. The southern portion of Africa, where the world's most diversified plant life is found, is also the home of the Namib Desert and the Kalahari Desert. The biggest desert of them all is the Sahara which is very close to the size of all of Australia. Succulent plants have adapted to survive in theses varying arid habitats. Most of them also do quite will in cultivation -- given the proper care that they require.
A suitable potting mix might be composed of a blend of 50% commercial, peat-based*, soil-less median and 50% expanded aggregate such as volcanic pumice, perlite, or vermiculite. An alternate mix might be two parts compost, two parts pumice, and one part sand. Experimenting with soil mixes is beneficial for compatibility with the watering schedule you become accustomed to, the fertilizer you use, and the climatic conditions that exist where you grow your plants. These soil mixes can retain some moisture while providing the air that succulent roots require. If soil tends to escape through drainage holes in your pots, it is advisable to use a piece of nylon window screen in the bottom of each pot.
With most succulents, water should be applied liberally so that the water will leach the salts out of the soil. The frequency of watering depends on the environment in which you live. Watering should be done less frequently in a damp environment than in a dry one. Watering becomes necessary when the plant's soil approaches dryness. Some growers wait until the soil is completely dry. Although this may be desirable with certain species, soil that has become too dry for too long tends to cause the roots to desiccate from lack of moisture.
Fertilizing can be accomplished by applying the recommended dosage on a balanced fertilizer about once a month; however, many growers prefer to use a fertilizer that has been diluted to about 1/4 strength at almost every watering. A balanced fertilizer is one with the listed N/P/K in balanced numbers such as 10/10/10 or 20/20/20. The center number (phosphorus) can be higher if the intent is to produce an abundance of flowers.
An abundance of information can be gleaned from the CSSA's newsletter and the Cactus & Succulent Journal. Seek out others with similar interests. Learning from other's trials and tribulations can be very beneficial. Join a club, read available materials, and experience the pleasure of growing succulent plants.
*mixtures with peat or peat moss must have good drainage to avoid rot. -- web editor