Cold hardiness & minimum temperature

Is Aglaonema Red (Aglaonema 'Red Siam')cold hardy? Hardiness zone & min temp

Also called Red Siam Chinese evergreen, red aglaonema.

More about aglaonema red

About Aglaonema Red

Aglaonema 'Red Siam' · also called Red Siam Chinese evergreen, red aglaonema · tropical

Aglaonema 'Red Siam' is a striking Chinese evergreen with broad leaves splashed in pink, rose and crimson over green. A tough, slow-growing tropical that tolerates low light and irregular watering, it is one of the most forgiving coloured houseplants. Note it is toxic to pets, containing insoluble calcium oxalate crystals.

Cold limit: USDA 10-12 (indoor in most US homes) · RHS H1b (18-29°C)

Watch for — Yellowing leaves: Most often overwatering or cold, soggy soil. Let the top third dry between waterings and keep it above 16°C; chilling causes yellowing and collapse.

What aglaonema red's hardiness rating actually means

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

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

Aglaonema Red hardiness — frequently asked questions

Is aglaonema red cold hardy?

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

What is the minimum temperature aglaonema red can survive?

What hardiness zone is aglaonema red?

Aglaonema Red is rated USDA 10-12 (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 aglaonema red 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 aglaonema red 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.