Cold hardiness & minimum temperature

Is Crassula Undulata (Crassula ovata 'Undulata')cold hardy? Hardiness zone & min temp

Also called ripple jade, curly jade.

More about crassula undulata

About Crassula Undulata

Crassula ovata 'Undulata' · also called ripple jade, curly jade · houseplant

Crassula 'Undulata', the ripple or curly jade, is a jade-plant cultivar with wavy, twisting blue-green leaves often edged in red. A slow-growing succulent shrub, it stores water in fleshy leaves, wants bright sun and gritty fast-draining soil, and needs only occasional deep watering. Striking and easy-care, but toxic to cats and dogs.

Cold limit: USDA 10-11 (indoor in most US homes) · RHS H1c (18-24°C)

Watch for — Overwatering and rot: Soggy soil rots roots and stems. Let the mix dry fully between waterings, use gritty compost and cut back water in winter.

What crassula undulata's hardiness rating actually means

Crassula Undulata 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). Crassula Undulata has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Crassula Undulata hardiness — frequently asked questions

Is crassula undulata cold hardy?

Crassula Undulata 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. Crassula Undulata 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 crassula undulata can survive?

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

What hardiness zone is crassula undulata?

Crassula Undulata 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 crassula undulata 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 crassula undulata 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.