Cold hardiness & minimum temperature

Is Earth Star (Cryptanthus bivittatus)cold hardy? Hardiness zone & min temp

Also called Earth Star Bromeliad, Starfish Plant.

More about earth star

About Earth Star

Cryptanthus bivittatus · also called Earth Star Bromeliad, Starfish Plant · tropical

The earth star is a flat, star-shaped bromeliad with wavy, banded leaves in green, pink and bronze that hug the ground. Unlike most bromeliads it is terrestrial and grows in soil, drawing water through its roots rather than a cup. It stays small, loves humidity and warmth, and shows its best stripes in bright indirect light.

Cold limit: USDA 11-12 (indoor in most US homes) · RHS H1b (18-27°C)

Watch for — Browning, curling leaf edges: Low humidity is the usual cause. Raise humidity with a tray, humidifier or terrarium and avoid dry, draughty spots.

What earth star's hardiness rating actually means

Earth Star 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 11-12 (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 10 °C (sustained cold below this is damaging). Earth Star has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Earth Star hardiness — frequently asked questions

Is earth star cold hardy?

Earth Star 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. Earth Star can only live outside year-round in genuinely frost-free climates (roughly USDA 11-12 (indoor in most US homes)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature earth star can survive?

Minimum survivable temperature is roughly about 10 °C (sustained cold below this is damaging). Earth Star has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

What hardiness zone is earth star?

Earth Star is rated USDA 11-12 (indoor 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 earth star 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 earth star 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.