Cold hardiness & minimum temperature

Is Slender-lined Living Stones (Lithops gracilidelineata)cold hardy? Hardiness zone & min temp

Also called Slender-lined Living Stones, Fine-lined Living Stones.

More about slender-lined living stones

About Slender-lined Living Stones

Lithops gracilidelineata · also called Slender-lined Living Stones, Fine-lined Living Stones · houseplant

Lithops gracilidelineata is a small, elegantly marked South African stone-mimic succulent with delicate, thin-lined patterning on its grey to pale olive tops. Considered one of the more challenging Lithops to grow, it requires very bright direct sun, extremely fast-draining soil, and precise seasonal watering to prevent rot during its mandatory dormancy periods.

Cold limit: USDA 10-11 · RHS H1b (10–38°C)

Watch for — Etiolation and pattern loss: Without sufficient direct sun, bodies stretch quickly and the delicate line patterning fades. Position under the strongest available light source and supplement with a grow lamp in winter months.

What slender-lined living stones's hardiness rating actually means

Slender-lined 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 10-11 — 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). Slender-lined Living Stones has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for slender-lined 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 slender-lined 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 slender-lined 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.

Slender-lined Living Stones hardiness — frequently asked questions

Is slender-lined living stones cold hardy?

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

What is the minimum temperature slender-lined living stones can survive?

What hardiness zone is slender-lined living stones?

Slender-lined Living Stones is rated USDA 10-11 and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can slender-lined 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 slender-lined 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.