Cold hardiness & minimum temperature

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

Also called Karas Mountains Living Stone, Flowering Stones.

More about living stones

About Living Stones

Lithops karasmontana · also called Karas Mountains Living Stone, Flowering Stones · houseplant

Lithops karasmontana is a mimicry succulent from Namibia's Karas Mountains, its paired fused leaves disguised as patterned pebbles. Each plant is mostly a single pair of leaves with a fissure that splits to reveal a daisy-like white flower in autumn. It demands extremely sparing water on a strict seasonal cycle and the grittiest possible drainage to thrive.

Cold limit: USDA 10-11 (indoor in most US homes) · RHS H1c (18-27°C)

Watch for — Bursting or splitting body: Watering during dormancy or while the new leaf pair is forming swells the plant until it splits. Withhold all water in summer and winter and only resume on the seasonal cycle.

What living stones's hardiness rating actually means

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 H1c means: Warm-temperate — can summer outdoors but must come in well before the first frost. On the US scale that maps to USDA 10-11 (indoor in most US homes) — 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 5 °C (and never frost). Living Stones has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for living stones as it gets too cold:

Below about about 5 °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 living stones go outside or overwinter — and where?

It can holiday outdoors in summer once nights are reliably above 5 °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 living stones can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Living Stones hardiness — frequently asked questions

Is living stones cold hardy?

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. Living Stones can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (indoor in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature living stones can survive?

Minimum survivable temperature is roughly about 5 °C (and never frost). Living Stones has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is living stones?

Living Stones is rated USDA 10-11 (indoor in most US homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can living stones survive winter outside?

It can holiday outdoors in summer once nights are reliably above 5 °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 living stones below its minimum temperature?

Below about about 5 °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.