Lithops

How the lithops year works

Each lithops is a single pair of fused leaves with a slit, the fissure, across the top. Once a year it grows a new pair inside the old one, and your watering has to follow that cycle. The seasons below are for the Northern Hemisphere; south of the equator, shift them by six months.

• Late summer to fall: growth and flowers. The fissure starts to open. That’s your signal to start watering.
• Winter to spring: the leaf change. A new pair grows inside, and the old pair shrivels as the plant reabsorbs it. Don’t water at all. The new pair opens at right angles to the old one, and the old leaves end up as a dry, papery skin. Some plants split into two heads at this point.
• Late spring to early summer: water again, but only once the old leaves are completely dry and shriveled.
• Midsummer: dormant. Stop watering. If a plant shrivels badly, give it just enough to wet the top half inch of soil.

They’re slow and long-lived, up to 40–50 years, and can stay in the same pot for a decade or more. ASPCA lists living stones as non-toxic to cats and dogs.

When to water lithops

In a watering season, drench the pot, let it dry out completely (often 1–2 weeks), then wait a couple more days. Water in the morning. If in doubt, don’t. Overwatering is the main cause of early death: the plants rot, or start new leaves at the wrong time of year. Watering during the leaf change is the classic mistake, because the old leaves try to keep growing and the new pair doesn’t develop properly. Too little water just stunts them.

Light, soil and pots

Lithops need sun: about 4–5 hours of direct morning sun, with some shade in the afternoon. A south window is best, or an unobstructed east one. In too little light they stretch, lean and lose their color. Move them into brighter light gradually, or they scorch.

Use a cactus mix with extra sharp sand or perlite, in a pot 3–5 inches deep with a drainage hole; the roots run deeper than the plant suggests. Set each plant with its top just above the soil. They handle serious heat if the air moves, but keep them above 40°F (4°C) and never let them freeze.

Lithops flowers

Lithops flower in fall and early winter. A daisy-like flower, yellow, white or pale orange and ½ to 1½ inches across, pushes out of the fissure. Flowers open in the afternoon on sunny days and close again by late afternoon, and some are scented. Lithops can’t pollinate themselves, so you need two different plants to get seed. Plants grown from seed can flower in 3–4 years.