Cold hardiness & minimum temperature

Is Haworthia (Haworthiopsis attenuata)cold hardy? Hardiness zone & min temp

Also called zebra plant, zebra haworthia, pearl plant.

About Haworthia

Haworthiopsis attenuata · also called zebra plant, zebra haworthia · houseplant

Haworthia (now mostly reclassified as Haworthiopsis) is a small rosette succulent from South Africa, well suited to windowsill culture because it tolerates lower light than most succulents. The "zebra plant" common name refers to white horizontal stripes on the leaves. Pet-safe by ASPCA standards.

Haworthia are small rosette succulents native to South Africa, many growing partly buried among rocks and grass tufts in semi-shade, with translucent 'window' tips on their leaves that admit light to the buried photosynthetic tissue.

A slow-growing, long-lived tender succulent preferring roughly 21-32C for best growth; it readily produces offsets (pups) around the base that can be detached to propagate clumps.

Cold limit: USDA 9-11 (indoor-only in most US homes) · RHS H1c (15-26°C)

Watch for — Red or purple flush: Sunburn or cold stress — move to gentler light.

Sources: gardeningknowhow.com, thesill.com

What haworthia's hardiness rating actually means

Haworthia 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-only 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 has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Haworthia hardiness — frequently asked questions

Is haworthia cold hardy?

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

What is the minimum temperature haworthia can survive?

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

What hardiness zone is haworthia?

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

Can haworthia 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 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.