Most arid plants are best given a position in full sun, either in the greenhouse, outdoors for the summer or, especially, when planted permanently out of doors. The growth is more compact, healthier and the plants, if they flower, will do so more freely. Air movement is important – succulent stems are very prone to rot in stagnant air.
Arid plants demand excellent drainage. Different growers will argue their corner for the exact best formula but, whatever you choose, it MUST be well drained. For greenhouse plants, or those grown outdoors but overwintered indoors, a mix of 2:1:1 of compost: sharp sand: grit is effective. Pumice, if you can get it, is perfect. For permanent planting positions outdoors it may sound cruel but a mix of pure grit or all-in-ballast (a mixture of sharp sand and 20mm grit) is effective. It is easier to add water than to remove it! Some arid plants are more tolerant of a richer soil mix; a few actually prefer it, so please refer to the species specific notes.
Feeding and Watering
A bright, sunny spot sheltered from strong winds is ideal, especially for species like Trachycarpus fortunei whose large fan-shaped leaves can be damaged in an exposed location. Some, such as Trachycarpus fortunei and Chamaedorea species can also be grown in a shaded position though the lower light levels result in the palm growing longer petioles (leaf stems).
Potted plants can be moved into the greenhouse, conservatory or cool windowsill indoors before the first frosts. In a bright position, kept dry, they can tolerate a few degrees below freezing – many cacti will flower better in spring following a cool, dry rest in winter as this is what they would experience in habitat.
There are exceptions, of course, so please check the species specific care notes. Plants that are suitable for growing permanently outdoors will nevertheless generally benefit from some kind of overhead rain cover to keep the crown of the plant and immediate root zone dry. There are many ways of doing this, including plastic bell cloches for smaller plants and pop-up mini-greenhouses for larger ones.