Age of Plant
Typically lithops (living stones) won’t flower until they are about 3 years old. Once they are the right age to flower some species of lithops will bloom in the late summer or early fall, and others in the late spring. As they grow, living stones should rebloom each year.
Time of Year
If your lithops plant is not flowering it might be due to the season and the climate. In the middle of a hot summer, the lithops might go dormant or partially dormant. This is a natural response of the plant during which it is conserving its energy and nutrients for when it is ready to flower. Similar behavior can also occur throughout the winter climate.
A proper watering schedule helps to feed the plant, allowing it to prepare for flowering and new growth. To get your lithops to this healthy stage you must water them when the soil volume is fully dry and the plants begin to wrinkle. You can further reduce watering in the winter, allowing the plant’s soil to dry fully between waterings.
When in doubt, it’s best not to water. Your lithops plant will shrink or wrinkle when it needs to be watered. Overwatering is much more dangerous than underwatering, similar to most succulents.
After the flowering period, it is possible your lithops will go into a naturally dormant state. This means it will use less water, so keep an eye on it and water if you notice the plant beginning to wrinkle or shrivel.
Lack of Sun
The lithops plant is native to rocky areas in southern Africa, so is used to long periods of drought and very little rainfall. This plant will thrive on a window sill where it can get direct sunlight. If your lithops is used to indirect light, acclimate it slowly over a couple of weeks to direct sunlight to avoid scorching the leaves.