Cold hardiness & minimum temperature

Is Wilmot's Dinteranthus (Dinteranthus wilmotianus)cold hardy? Hardiness zone & min temp

Also called Wilmot's Dinteranthus, Pebble Plant.

More about wilmot's dinteranthus

About Wilmot's Dinteranthus

Dinteranthus wilmotianus · also called Wilmot's Dinteranthus, Pebble Plant · houseplant

Dinteranthus wilmotianus is a South African stone-mimicry succulent closely related to Lithops, forming pairs of rounded, cream to pale grey leaf bodies with fine patterning that camouflages brilliantly among quartz pebbles. Large yellow flowers appear in autumn. It demands exceptional drainage, direct sun, and strict summer drought. Non-toxic and pet-safe.

Cold limit: USDA 10–11 (indoor-only in virtually all climates) · RHS H1c (8–35°C)

What wilmot's dinteranthus's hardiness rating actually means

Wilmot's Dinteranthus 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-only in virtually all climates) — 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). Wilmot's Dinteranthus has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for wilmot's dinteranthus 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 wilmot's dinteranthus 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 wilmot's dinteranthus can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1c figure above.

Wilmot's Dinteranthus hardiness — frequently asked questions

Is wilmot's dinteranthus cold hardy?

Wilmot's Dinteranthus 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. Wilmot's Dinteranthus can only live outside year-round in genuinely frost-free climates (roughly USDA 10–11 (indoor-only in virtually all climates)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature wilmot's dinteranthus can survive?

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

What hardiness zone is wilmot's dinteranthus?

Wilmot's Dinteranthus is rated USDA 10–11 (indoor-only in virtually all climates) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can wilmot's dinteranthus 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 wilmot's dinteranthus 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.