Lithops, also known as "living stones," are cacti native to Africa. The name lithops is Greek for "stone-like," which is a fitting description, as the plant has evolved to blend in with stones and rocks to avoid predators. The growth cycle of lithops begins when the body of the cactus splits into two parts. A flower stalk emerges from the center and the two bodies wither and die while a new body is forming at the base of the flower. The cycle continues each growing season. Lithops cacti have specific water requirements, but are relatively care free.
Keep lithops in a sunny windowsill that receives four to five hours of direct morning sunlight and partial afternoon shade. Use a planting medium made up of one part perlite to one part potting soil to increase drainage.
Keep lithops cactus at a temperature between 70 and 80 degrees F during summer, and between 55 to 65 degrees during winter. Never expose the cactus to temperatures below 40 degrees, or permanent damage can occur. Monitor the temperature at all times with a thermometer.
Water lithops between late spring and early summer. Cease watering during mid-summer, and resume again in early fall when the cactus begins to die. Do not water during winter or early spring.
Soak the soil thoroughly at each watering, and then wait about 20 days for the soil to dry out completely before watering again. Apply water during the early morning so excess moisture can evaporate before temperatures drop.
Feed lithops once every two months using a 5-10-20 NPK fertilizer. Follow the manufacturer's instructions for proper dosage. Do not fertilize during winter, as the cactus will not use the nutrients.