Lithops are truly a unique group of plants. Staying extremely low to the ground (sometimes almost entirely buried in it), Lithops resemble smooth pebbles. Their colour adds to this illusion as they sit in gorgeous clusters of pale beige, green, and brown. All of this is responsible for their nickname, 'Living Stones'.
Each individual typically only has one, sometimes two, leaf sets. The leaf is split into two general sections: the opaque tissue which covers the sides of the leaves (and is often at least partially buried in the dirt), and the translucent or mottled tissue covering the top of each leaf. These translucent sections are called fenestrations, and they serve an important purpose. Rather than containing chlorophyll themselves, these translucent cells allow light through to the inside walls of the plant, where chlorophyll-lined cells lie in wait to capture and use it.
This window strategy is one used by many desert plants including fenestraria and haworthia. It has several benefits, the most notable of which is that it allows the majority of the plant to remain hidden in the soil where it is protected from cattle and grazers, extreme heat, and also better able to retain moisture due to the lack of exposure.
There are generally two camps of people: those who love lithops and those who can't stand them (usually because they can't keep them alive).
Luckily with a few tips, you can join the first group and get to appreciate this extremely low-maintenance, diverse, fascinating group of plants. Firstly is light. Lithops are native to arid Southern Africa, and therefore love to be blasted with bright light and heat. Ofcourse, they will tolerate lower light (like many succulents) however we recommend a bright windowsill for these guys. Burning is not really an issue, as it would take quite a strong light source and very close proximity to cause a burn in Lithops.
Perhaps most importantly (at least the most common cause of death for Lithops) is watering. In short, Lithops really don't like water. They are not a good 'pet' for those of us who like to tend and nurture. They are however excellent teachers of patience, and they will reward your neglect with adorable new leaves and even flowers.
In addition to growing slowly and teaching patience, Lithops are very in tune with the seasons. They typically grow new leaves and/or flowers in late summer, and go dormant immediately after for several months until the next spring. While growing (typically beginning late spring and going through the summer), Lithops like a drink of water every few weeks, making sure the soil has completely dried in between. You may continue to water until early fall at which point the Living Stone will go dormant. During this time it is critical not to water the lithops (leave the soil completely dry, very occasionally misting the surface of the soil only - although even this is not necessary). Once the spring growth begins again, watering can resume.
Lithops don't require any fertilizer, and will likely do best without it.
For planting, use very quick draining and chunky soil containing lots of mineral content such as sand, perlite, charcoal, fine stone, etc.
When growing normally Lithops will shed their outer leaves yearly. You can remove them manually, taking care not to damage the young new leaves.
If you neglect your lithops a bit too much and the outer leaves begin to rot/look damaged/dry out, you can resort to something slightly extreme. Removing the entire plant and shaking it free of soil, hold the lithops with both thumbs placed on either cheek of the 'butt'. Carefully spread your thumbs and peel back the leaves, hopefully revealing a shiny new pair of leaves inside. Leave the old leaves partially attached at the base and replant the Lithops, hopefully to grow anew.