Succulents are plants with some fleshy parts –, or . This is not an end in itself, but an extraordinarily ingenious adaptation to the environment in which these plants live. The succulent parts serve as reservoirs of water to enable the plants to survive the uncongenial conditions of their natural habitats – arid places exposed to the full heat of the sun and with only occasional rain.
are all plants of the Cactaceae family. Other succulents belong to a wide variety of different families in which, for example, only the members of a single genus may be succulent; or even just some species of certain genera, such as the commonly grown pelargoniums. Major families of succulents are the Euphorbiaceae, in which some species resemble , Aizoaceae, which include the familiar living stones of the genus Lithops, Asteraceae and Liliaceae.
It is not possible to give general rules for the cultivation of succulents because of their immense range. Therefore, details are given separately in the text accompanying each illustrated species., however, are an exception. Although many species are undemanding with no special requirements, they must all be provided with certain basic conditions. First of all they require sun. Those without a sunlit window should not try to grow cacti. A , conservatory or miniature conservatory is ideal. The should be well permeable, preferably a mixture of rotted mould, frame soil, loam and sand. Cacti grown in an inert medium, such as crushed brick, should be given a regular application of special . Water fairly freely in summer (cacti tolerate more moisture than one would think). In winter severely restrict or even withhold it altogether. Cacti require a consistent low winter temperature of about 5°-10°C (41°-50°F).