Lithops care guide

A plant that runs on its own calendar

Lithops come from the dry parts of southern Africa, mainly South Africa and Namibia, where rain is scarce. Each plant is a pair of thick, fused leaves shaped like an upside-down cone, with a slit across the top and almost no stem. In the wild they sit almost flush with the ground and look like pebbles. The leaves store enough water to last for months, and a plant can live for 40 years or more.

Its yearly cycle decides everything. After flowering, a new pair of leaves starts to form inside the old pair. Through winter and spring the plant draws water and food from the old leaves, which shrivel into a papery skin while the new pair pushes out of the slit. Watering during this time keeps the old leaves alive and upsets the change. Overwatering is the main reason lithops die. The zebra haworthia, another small South African succulent, is far more forgiving about water.

Daisy-like yellow, white or pale orange flowers appear from the slit, mostly in autumn, and open on sunny afternoons. Over the years one plant can divide into a small cluster of heads. You can lift a cluster and carefully split it, or grow new plants from seed, which may flower after three or four years.

Follow the plant, not the calendar. In winter and spring, while the new pair grows and the old pair shrivels, give no water at all. Once the old leaves have dried to a papery skin, usually in late spring, you can start watering. In the hottest part of summer it rests, so water very sparingly or not at all. If it shrivels badly then, give just enough to wet the top centimeter or so of the mix. Water more regularly from late summer, when the slit starts to open, into autumn. Stop once flowering is over.

When you water, soak the mix, then let it dry out completely, which can take one to two weeks, and wait a few more days before you water again. Water in the morning. If you are in doubt, do not water. Some wrinkling is normal when the old leaves are being used up or the plant is resting. Leaves that turn yellow, soft or mushy, or a plant that splits open, mean it has had too much water.

Give it as much light as you can. Four to five hours of direct morning sun with some afternoon shade is ideal, and a south window is best. An unobstructed east window also works. In too little light it stretches, leans, turns greener and loses its markings. Move a plant to stronger sun gradually so it does not burn.

Feed sparingly, and only while it is growing. A low-nitrogen, high-potassium feed at half strength a few times in the growing season is plenty. Never feed it while it rests or while the new leaves form.

It grows best at about 18 to 27 °C (64⁠–⁠81 °F). It tolerates heat well as long as the air moves, but it must never freeze, so keep it above 5 °C (41 °F). A cool, bright windowsill in winter suits it while it is kept dry.

It needs no extra humidity. It comes from dry regions, and ordinary dry room air suits it. There is no need to mist it. Good air movement helps, especially in hot weather.