Cold hardiness & minimum temperature

Is Stromanthe Triostar (Stromanthe thalia 'Triostar')cold hardy? Hardiness zone & min temp

Also called Stromanthe Triostar, Triostar Stromanthe, Tricolor Prayer Plant, Magenta Triostar, Stromanthe sanguinea 'Triostar'.

More about stromanthe triostar

About Stromanthe Triostar

Stromanthe thalia 'Triostar' · also called Stromanthe Triostar, Triostar Stromanthe · houseplant

Stromanthe Triostar is a Brazilian prayer plant (Marantaceae) prized for cream, green and magenta variegated leaves that fold up at night. Give it bright indirect light, consistently moist soil watered with filtered water, and high humidity. It is not individually listed by the ASPCA, so verify pet safety with your vet before trusting it around pets.

Cold limit: USDA 10-12 (grown as a houseplant in cooler zones) (18-27 C)

Watch for — Curling or folding leaves that stay shut by day: A sign of dry air, underwatering or sudden temperature swings. Keep soil evenly moist and protect from drafts and heat sources.

What stromanthe triostar's hardiness rating actually means

Stromanthe Triostar 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 10-12 (grown as a houseplant in cooler zones) — 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). Stromanthe Triostar has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Stromanthe Triostar hardiness — frequently asked questions

Is stromanthe triostar cold hardy?

Stromanthe Triostar 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. Stromanthe Triostar can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (grown as a houseplant in cooler zones)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature stromanthe triostar can survive?

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

What hardiness zone is stromanthe triostar?

Stromanthe Triostar is rated USDA 10-12 (grown as a houseplant in cooler zones) and RHS H1c — Warm-temperate — can summer outdoors but must come in well before the first frost.

Can stromanthe triostar 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 stromanthe triostar 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.