An important factor in determining the suitability of a plant to your home and envisioning the care it will need, is to know the origin of the plant. Plants that are native to desert regions will require substantial amount of sunlight and loose, fast-draining soil. Plants from the floor of a rainforest will need some protection from strong sunlight and generous humidity.
Lithops are succulent, desert natives consisting of a single pair of mostly-fused leaves. The unbranched body is thick and closely resembles a divided stone in shape and color. It is attached to a short stem that is buried in its growing medium along with a longer taproot. They may produce a flower in late summer or fall from the division across the top of the plant.
All 300+ varieties of living stone plants require the excellent drainage and strong sun that is typical of a desert habitat. After flowering, they rest before forming a new set of leaves to replace the old. Their watering regime is critical.
Living stones prefer plentiful sunlight, all year long. Light is where many succulent gardeners fall short of the needs of their plants. It is crucial that you place this plant in a window where it will receive a minimum of six hours of sunlight per day. Without extended, direct light, your plant will lose its attractive form. A living stone plant should continue to receive bright light even during its winter rest period.
If the sun in your sunniest window is not adequate, artificial lights should be considered, alone or in combination with natural light. A white fluorescent light, 6 to 12 inches above the plant will give good results. Artificial light is not equivalent to daylight in strength and must be delivered for at least 14 to 16 hours per day.
Too much water is the most frequent cause of lithops failure. In spring and summer, water only in dribbles to keep barely moist. When a bud appears, water deeply but infrequently to keep just turgid. Do not water at all after flowering and during emergence of new leaves or it will disrupt the process.
Average household humidity is fine but separate these plants from any leafy ones getting extra misting. Good air circulation is a must.
Normal room temperatures are appropriate. Keep above 50º F.
Living stones require a deep pot for the long tap root. They grow slowly and do not need to have their soil and pot refreshed until they begin to crowd their space, about every four years. The proper, quick-draining, soil, however, is essential. Soil should resemble the loose, free-draining mixture of a native, desert habitat. Equal parts potting soil and sand are generally best. Commercial cactus mixes are acceptable, but avoid those that have food already in the mix. A layer of pebbles at the bottom of the pot for drainage and at the top, to prevent leaf contact with wet soil, is advisable. Your pot must have a draining hole at its bottom.
Feeding is unnecessary.Living stone plants get the limited nutrition they need from the soil.
After flowering, the leaves generally die back and are replaced by new ones.
Fungal stem rot can affect plants, particularly if they are exposed to too much water or humidity or extremes of temperature.
The Houseplant Survival Guide by 
