Growing lithops at home is an uncomplicated task if the natural cyclic growth of the plant is taken into account. A lack of knowledge about the biology of the succulent leads to improper care and, consequently, its demise. The unusual annual growth cycle of lithops consists of four periods, each corresponding to its own rules of care and watering: growth period, dormancy period, flowering period, renewal period. The most crucial factor for maintaining lithops is proper watering in accordance with the periods of its life cycle.
During the dormancy period from June to August (in nature, the dry season with long daylight hours), lithops does not grow, does not bloom, and sometimes sinks completely into the ground. At this time, the plant, being in a dormant state, does not need watering and uses moisture accumulated during the growth period. If the leaves wrinkle, careful moistening of the top 1 cm (0.4 in) layer of soil is permitted. In early August, fine misting of the plant in the morning hours is allowed. In natural conditions, lithops tolerates temperatures up to 50 °C (122 °F), but the optimal range during this period is 23-28 °C (73-82 °F).
During the flowering period from August to October (in nature, the rainy season with decreasing daylight hours), lithops awakens, begins intensive growth, produces a peduncle from the fissure between the leaves, blooms, and begins fruit maturation, which lasts several months. From mid-August, watering is resumed and increased. The plant is watered generously but rarely, with mandatory complete drying of the soil. Abundant moistening stimulates flowering in lithops older than 3 years. With the end of flowering, watering is reduced for a smooth transition of the plant into the next cycle period. During this period, it is necessary to maintain a temperature of at least 20 °C (68 °F).
During the renewal period from October to March (in nature, the dry season with short daylight hours), after flowering ends, lithops enters a state of slow growth, which many mistakenly call a second dormancy period. The plant continues to develop slowly, but this process is visually imperceptible; moreover, it may seem that the plant is dying, but this is the new pair of leaves beginning its vegetation, forming at the growth point of the old pair. New leaves grow inside the old ones, drawing out their nutrients. Over time, the old pair wrinkles, dries up, thins out, and tears open, releasing the young leaves. At this time, the plant does not need watering or moistening, but requires good lighting and keeping at a temperature of 10-15 °C (50-59 °F), not below 7 °C (45 °F). Watering ceases completely until early March.
During the growth period from March to June (in nature, the rainy season with increasing daylight hours), the new pair of succulent leaves that has taken the place of the old one begins the process of active vegetation. The emergence and development of new leaves begins a new life cycle of the lithops, while dying old leaves conclude the previous one. Watering is carefully resumed and gradually increased during March, brought to a maximum by mid-April, and reduced by the end of May. The plant increases in volume due to the accumulation of moisture. From the beginning of spring, a temperature around 20 °C (68 °F) is optimal.
Watering must be careful and moderate, with drying of the soil between waterings. Excess moisture can lead to rotting of leaves and roots. Experienced growers water from the tray or by the immersion method, draining excess water after 10 minutes. For beginners, these methods are not recommended; it is better to use a fine spray bottle to moisten the soil and air, but it is very important that moisture penetrates deep into the container, as lithops has a long root. Water must not be allowed into the fissure between the leaves, as this can provoke rot or sunburn. Water used should be filtered or settled, soft and warm. Lithops is indifferent to air humidity; spraying can be used as humidification during transitional stages between periods. The plant requires fresh air and regular room ventilation without drafts.
Lithops require bright sunlight throughout the entire year. Being under direct sunlight on a south, southeast, or east window for 4-5 hours in the first half of the day, followed by partial shade in the second half of the day, will be sufficient. As an alternative, 12-hour artificial lighting with fluorescent or LED lamps located at a distance of 10-15 cm (4-6 in) from the plant is acceptable. West and southwest windows are less acceptable, while north windows cannot be used at all, nor should plants be placed in the depth of a room. In early spring, lithops growing on a south window should be shaded for 1-2 weeks to avoid burns. Plants deprived of light for 4-5 days become thin, stretch, lose color vibrancy, and may perish. With systematic lack of light in summer, the plant will not bloom. Changing location is not recommended.
Lithops grow slowly and need repotting once every 3-5 years in spring or summer. For planting, wide light-colored containers with a depth of 6-8 cm (2.4-3.1 in) are chosen, with an obligatory drainage layer of about 2 cm (0.8 in) at the bottom. In clay pots, drainage is not mandatory. The container size is chosen slightly larger than the size of the root system. They are planted in groups of 3-5 plants, since in solitary placement they develop much worse and rarely bloom. The top layer of soil is sprinkled with various decorative stones and pebbles as prevention against root collar rot.
The substrate should be rocky, poor, loose, and possess neutral acidity. Due to a high peat content, using ready-made cactus soils is not recommended. A mixture of light sod soil with coarse sand or fine gravel in equal parts is used. A more complex mixture can also be used, consisting of 2 parts sod soil, 1 part leaf humus, 3 parts coarse river sand, and 2 parts crushed brick. The prepared substrate must be disinfected before planting.
Lithops are capable of obtaining all necessary nutrients from water and soil; consequently, feeding is not obligatory. But if the plant has not been repotted for more than 2-3 years, special fertilizers for cacti and succulents in half dose during watering can be used. Feeding can be done twice a year: in early May and in late August.
With proper care, lithops rarely get sick or fall prey to pest attacks. During winter, plants can be damaged by fungus gnats, spider mites, and mealybugs. There are various folk remedies for combating these pests, but it is more effective to use commercial insecticide preparations according to instructions. Lithops get sick and perish most often from stem and root rot caused by excess moisture resulting from improper watering and poor drainage. In case of disease, watering must be sharply reduced and the plant treated with fungicides against fungi.