Once you get a handle on the basic requirements, growing them will quickly become an obsession. Lithops grow well in shallow containers in a controlled climate environment such as a greenhouse.
The annual cycle of a lithops begins in late spring, when in response to moisture the existing leaf pair starts to increase in size. Depending on species, at some time between July and December in the northern hemisphere, a single flower bud will force its way through the fissure and open to a daisy-like flower that can be as large as the plant body and lasts for about a fortnight.
Lithops require a very bright and sunny position at all times, but during particularly warm summer periods this must be accompanied by good ventilation to prevent scorching. In common with most succulent plants, the stomata only open at night to allow absorption of carbon dioxide. This normally occurs below about 18oC, therefore also maintain plenty of ventilation at night during warm weather. In the wild, some species experience frost for short periods. However, in cultivation, it is safer to keep them frost-free and most growers try to maintain a minimum temperature of 4 - 5oC in their greenhouses.
The summer watering is started when the new leaves are well developed and the old leaves more or less dried up; in United Kingdom greenhouses this tends be sometime during May. Pots are allowed almost to dry out before the next watering and the process is continued until October. During high summer, watering will usually be required at least once per week. Pots are kept completely dry through the winter until the next May, but growers in warmer climates such as California sometimes need to give a very small amount of water during this period. Occasional feeding with a low-nitrogen liquid fertiliser during the growing season is advantageous.
Lithops prefer a soil mixture that is made up of sandy gravel (e.g. 2 parts sand: 1 part clay loam: 1 part gravel). Add bone meal (phosphorus, like powdered dried chicken bones) and dolomitic lime (calcium, magnesium)