Cold hardiness & minimum temperature

Is Fishbone Cactus (Epiphyllum anguliger)cold hardy? Hardiness zone & min temp

Also called Zigzag Cactus, Ric Rac Cactus.

More about fishbone cactus

About Fishbone Cactus

Epiphyllum anguliger · also called Zigzag Cactus, Ric Rac Cactus · houseplant

The fishbone cactus is a Mexican epiphyte grown for its deeply zigzagged, flat green stems that trail like a fish skeleton. Easy and forgiving, it thrives in bright indirect light, an airy fast-draining mix, and moderate watering, rewarding a cool dry winter with fragrant night-opening flowers. A spineless jungle cactus and ASPCA-listed non-toxic to pets.

Cold limit: USDA 10-12 (grown indoors in most US homes) · RHS H1b (16-27°C)

Watch for — No flowers: Needs maturity, bright indirect light, and a cool, drier winter rest to bloom. Provide that rest period and adequate light, and be patient with younger plants.

What fishbone cactus's hardiness rating actually means

Fishbone Cactus 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 10-12 (grown indoors 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 10 °C (sustained cold below this is damaging). Fishbone Cactus has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

Concretely, for fishbone cactus 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 fishbone cactus 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 fishbone cactus can be outside. US growers can check USDA zones; UK growers should use the RHS hardiness ratings, which match the H1b figure above.

Fishbone Cactus hardiness — frequently asked questions

Is fishbone cactus cold hardy?

Fishbone Cactus 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. Fishbone Cactus can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (grown indoors in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature fishbone cactus can survive?

What hardiness zone is fishbone cactus?

Fishbone Cactus is rated USDA 10-12 (grown indoors in most US homes) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can fishbone cactus 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 fishbone cactus 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.