During the summer months, Lithops become dormant, resting as they do in the wild, although as a houseplant the conditions are not so severe. The plants require little or no water when they are dormant. Regular watering during this period would almost surely cause them to suddenly rot and turn into mush. But if a prominent shrivelling occurs during the summer, it is safe to give just enough water to restore the firm appearance of the plant. Water lightly so that about only the top one-half inch or so of the soil is moistened. Never water deeply when the plants are dormant.
In the fall, usually in August or September, the plants will begin growing. The first sign of growth is noticed when the fissure between the leaves begins to separate. In the days to follow, a bud will force its way up through the fissure and shortly thereafter a white or yellow flower will unfold. The flowers of many of the Lithops species have a spicy-sweet scent. Water deeply from August to late September to mimic the rainy seasons of the lithops' native Africa. Water the plant thoroughly before letting the soil dry out again. Stop watering your lithops altogether in late September.
If a plant does not flower the first year, perhaps it is not quite old enough. Lithops usually must be three to five years old before they begin flowering: they have been grown as seedlings for two years or more in the nursery. As the fissure separates further, a new pair of leaves can be seen developing inside. As the plant becomes older, it increases in size by division. This will begin by one plant producing two pairs of new leaves. The plant will then have two "bodies" attached to one root system. Some plants in Lithops collections have as many as ten or more bodies per plant, but it takes many years to develop a plant of this size.