Cold hardiness & minimum temperature

Is Cryptanthus bromelioides (Cryptanthus bromelioides)cold hardy? Hardiness zone & min temp

Also called rainbow star, rainbow earth star.

More about cryptanthus bromelioides

About Cryptanthus bromelioides

Cryptanthus bromelioides · also called rainbow star, rainbow earth star · tropical

Cryptanthus bromelioides is a Brazilian terrestrial bromeliad—an earth star—forming a flat, star-shaped rosette of wavy-edged leaves, often striped cream, pink and green in its 'Tricolor' form. Unlike tank bromeliads it grows in the ground and is watered through its roots and crown. It needs bright indirect light, a moist but well-drained mix, and warm, humid air.

Cold limit: USDA 10-11 (indoor/terrarium in most US homes) · RHS H1b (18-27°C)

Watch for — Leaf spotting: Hard tap water and cold drafts mark the foliage. Use low-mineral water and keep it warm and stable.

What cryptanthus bromelioides's hardiness rating actually means

Cryptanthus bromelioides 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 10-11 (indoor/terrarium 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). Cryptanthus bromelioides has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Cryptanthus bromelioides hardiness — frequently asked questions

Is cryptanthus bromelioides cold hardy?

Cryptanthus bromelioides 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. Cryptanthus bromelioides can only live outside year-round in genuinely frost-free climates (roughly USDA 10-11 (indoor/terrarium in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature cryptanthus bromelioides can survive?

What hardiness zone is cryptanthus bromelioides?

Cryptanthus bromelioides is rated USDA 10-11 (indoor/terrarium 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 cryptanthus bromelioides 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 cryptanthus bromelioides 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.