Cold hardiness & minimum temperature

Is Haworthia Obtusa (Haworthia obtusa)cold hardy? Hardiness zone & min temp

Also called Blunt-leaved haworthia, Globe haworthia.

More about haworthia obtusa

About Haworthia Obtusa

Haworthia obtusa · also called Blunt-leaved haworthia, Globe haworthia · houseplant

Haworthia obtusa (within the H. cooperi complex) forms plump rosettes of rounded, almost translucent blue-green leaves that glow like glassy beads when backlit. This 'window plant' prefers bright filtered light and gritty soil, and the puffy leaves shrink when thirsty. It stays small, offsets into clumps, and is pet-safe.

Cold limit: USDA 9-11 (indoor in most US homes) · RHS H1c (18-27°C)

What haworthia obtusa's hardiness rating actually means

Haworthia Obtusa 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 9-11 (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). Haworthia Obtusa has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Haworthia Obtusa hardiness — frequently asked questions

Is haworthia obtusa cold hardy?

Haworthia Obtusa 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. Haworthia Obtusa can only live outside year-round in genuinely frost-free climates (roughly USDA 9-11 (indoor in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature haworthia obtusa can survive?

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

What hardiness zone is haworthia obtusa?

Haworthia Obtusa is rated USDA 9-11 (indoor in most US homes) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can haworthia obtusa 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 haworthia obtusa 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.