My very first entry in a cactus show. Third place ribbon, Mamillaria rhodantha. Central Florida Cactus and Succulent Society Sale and Show September 1994.

All cacti belong the Cactaceae family.  The presence of areoles
is what identifies the plant as cacti.  The areoles are only 
possessed by cacti.  There are three subfamilies to the Cactaceae
family: Pereskioideae,Opuntiodeae and Cereoideae.  

In the Cactaceae family there are approximately 150 genera and
about 2,500 species.  Because of differing expert opinion it is 
hard to determine the exact genera and species of all cacti.

Planting and Repotting

It is best to repot cacti in the spring or during their resting
period at the end of July and early August.  The soil should be
mixed with equal parts of sand.  The pot should be as deep as it 
is wide.  Some recommend plastic pots as the water is not absorbed
by the pot, but I use clay and have had nothing but success with them.

Watering

Cacti, like no other plant can survive with little or no water.
How often the plant should be watered depends on the circumstances.
Not only the size of the plant but the size of the container
determine how much to water.  Adult plants can go for up to a month 
without water while smaller plants need watering more often.

In the winter water should be withheld altogether.  In spring
watering can be liberal.  In hot summer many cacti suspend growth
and watering should be limited.

DO NOT water when the soil is moist as it may destroy the whole plant.
It is better to water less frequently and liberally than light 
and often.
If it is warm and dry water more frequently.  If it is cold and rainy
with hold water altogether.

This guide is for the amatuer grower.  That is the only experience I have with 
any of the plants I grow.  I have lost a few plants through trial and error
but fortunately they were inexpensive.  I have just begun to collect some 
of the more rare cacti and also caudex succulents.

 More information on Cacti can be found in the following books:

The Cactus Primer by Arthur C. Gibson & Park S. Nobel
The World of Cacti by Danny Schuster
The Illustrated Guide to Cacti by Rudolf Slaba
The Complete Book of Cacti and Succulents by Terry Hewitt