Cold hardiness & minimum temperature

Is Karas Mountains Living Stones (Lithops karasmontana)cold hardy? Hardiness zone & min temp

Also called Karasberg Living Stones, Stone Plant, Mimicry Plant.

More about karas mountains living stones

About Karas Mountains Living Stones

Lithops karasmontana · also called Karasberg Living Stones, Stone Plant · houseplant

Lithops karasmontana is a remarkable stone-mimicking succulent from Namibia's Karas Mountains, forming pairs of fused, pebble-like leaves with intricate grey-brown patterns. It produces white or pale yellow flowers in autumn. Strict watering discipline is critical — overwatering during the wrong season kills it. The ASPCA has previously listed Lithops as non-toxic to dogs and cats.

Cold limit: USDA 10–12 · RHS H1b (10–35°C)

What karas mountains living stones's hardiness rating actually means

Karas Mountains Living Stones is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Its RHS rating of H1b means: Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season. On the US scale that maps to USDA 10–12 — the zones where it can be left outdoors year-round.

New to these scales? The USDA hardiness zone map explained covers how the zone numbers work, and you can find your own zone with the zone finder.

Minimum temperature — and what happens below it

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Karas Mountains Living Stones has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for karas mountains living stones as it gets too cold:

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches.
A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover.
Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.

Can karas mountains living stones go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually.
Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C.
It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

Work back from your local frost dates with the frost-date calculator: the last spring frost and first autumn frost are what really decide when karas mountains living stones can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Karas Mountains Living Stones hardiness — frequently asked questions

Is karas mountains living stones cold hardy?

Karas Mountains Living Stones is not cold hardy. It is a tropical houseplant that dies if it is left out through frost — there is no zone where it overwinters outdoors in a UK or cold-US climate. Indoor-only in almost every home. Karas Mountains Living Stones can only live outside year-round in genuinely frost-free climates (roughly USDA 10–12); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature karas mountains living stones can survive?

What hardiness zone is karas mountains living stones?

Karas Mountains Living Stones is rated USDA 10–12 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can karas mountains living stones survive winter outside?

It can holiday outdoors in summer once nights are reliably above 10 °C, in shade or dappled light, hardened off gradually. Bring it back indoors well before the first autumn frost — do not wait for a frost warning, move it when nights drop toward 10-12 °C. It will never overwinter outside in a temperate climate; the indoors is its winter home, full stop.

What happens to karas mountains living stones below its minimum temperature?

Below about about 10 °C, growth stalls and the leaves start to show cold stress — dark, water-soaked, or yellowing patches. A single light frost blackens the foliage; a hard freeze kills the whole plant, roots included, and it does not recover. Even a cold, draughty windowsill or an unheated porch in winter can be enough to damage it permanently.