Cold hardiness & minimum temperature

Is Cob Cactus (Lobivia famatimensis)cold hardy? Hardiness zone & min temp

Also called Cob Cactus, Orange Cob Cactus.

More about cob cactus

About Cob Cactus

Lobivia famatimensis · also called Cob Cactus, Orange Cob Cactus · houseplant

A small, slow-growing globular cactus from the high-altitude grasslands and rocky soils of northwestern Argentina, with 24–40 neatly tidy ribs and short pectinate spines. Despite its modest size it produces an outsized show of funnel-shaped flowers in yellow to burnt orange in early summer. Requires a cold, dry winter rest to trigger flowering the following season.

Cold limit: USDA 9-11 · RHS H1c (5–30°C)

Watch for — No flowers: The most common complaint. Blooming requires a cold (5–10°C), dry winter rest from October to February. Plants kept warm and moist year-round will not flower. Reduce water to almost nothing and move to the coolest indoor spot for the winter months.

What cob cactus's hardiness rating actually means

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

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

Cob Cactus hardiness — frequently asked questions

Is cob cactus cold hardy?

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

What is the minimum temperature cob cactus can survive?

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

What hardiness zone is cob cactus?

Cob Cactus is rated USDA 9-11 and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can cob cactus 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 cob cactus 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.