Watering : Watering properly is one of the most important factors in cactus culture. Soil mixture, containers, drainage, temperature, size of plant and type of plant all influence water use, so no absolute schedule can be given for watering.

Careful observation is the best way to determine a plant's water needs. During the active growing season (spring and summer), the soil should be thoroughly wetted at each watering, and allowed to dry before water is added again. Keep in mind that rain may count as watering if plants are kept outside depending on the amount of rain.

Dormant cacti need less moisture. A light watering every few weeks is sufficient during the inactive season (late fall and winter.) Do not soak the soil during the dormant period.

Soils : Good drainage is essential in any soil mix, yet the soil mix also must have moisture retention properties, along with adequate nutrients. A general growing medium for arid species of cacti consists of 1/2 potting soil and 1/2 Perlite or other material that provides for good drainage. Gravel works, but makes the pot heavier than with Perlite.

Cacti should be repotted as needed, rather than on a regular schedule. Repot if the cactus plant is within 1/4 inch of the container wall or edge of the soil ball. Repot into a container only slightly larger than the present one. Repotting into a container too large may lead to a tendency to over water. Also, cacti seem to prefer to be a little snug in the pot.

Set the plant in the new container at the same level it was originally growing and fill around it with soil mixture. Wait several days before watering so damaged roots will have time to heal.

Fertilizer : Like other types of house plants, cacti need fertilizer, but in smaller amounts (about ½ to ¼ strength.) From spring to fall they can be fertilized every month or so with a low nitrogen fertilizer such as 5-10-10. Time-released fertilizers also can be used, but need only be applied once in the spring. Do not fertilize newly repotted plants, un-rooted plants, or plants going through a dormancy period. Too much fertilizer is worse than none at all.

Light : Most arid species of cacti require bright sunlight to grow well. Windows facing south provide the most sunlight, while windows facing east and west usually offer some direct sun for at least part of the day. In some homes, artificial light may be necessary to supplement natural light. During the warmer months, plants can be set outside in full sun to filtered sun to bright shade, depending on the type of plant. Remember to bring the plants inside for the winter if they are not cold hardy.

Temperature : Proper temperatures for raising cacti vary with the season. Arid cacti plants tolerate temperatures of 90-100°F during the active growing season. They can be placed outdoors in late spring, but for several weeks may need to be shaded during the hottest part of the day until they adjust to the temperatures and higher light intensities. Many of the succulent plants prefer to be kept in bright shade to filtered sun. In the early fall it is necessary to bring non-cold hardy plants indoors before a frost.

Dormant cactus plants do best at temperatures from 45-55°F. The cooler temperatures develop sturdier plants and encourage the formation of flower buds. Cool winter temperatures are not a necessity for cactus plants, but these conditions approach the environment in which cacti normally grow. Convenience often will decide the temperature at which cacti plants are maintained.

Diseases and Pests : The major diseases of cacti are root and/or stem rots. Excessive watering should be avoided to prevent these rots. Make sure there is good air circulation between plants.

Insect and related pests on cacti include aphids, red spider mites and mealy bugs. Make sure newly purchased plants are free of pests before they are added to your plant collection.

If insects or mites do become established on your plants, consider using a registered insecticide or miticide to rid the plants of these pests. Often, a spray made from water with a small amount of dish washing liquid and alcohol will kill pests.

Additional Information : The internet is a valuable source of information regarding general care as well as information about specific plants.