Cold hardiness & minimum temperature

Is Zamia Roezlii (Zamia roezlii)cold hardy? Hardiness zone & min temp

Also called Roezl's zamia, Colombian zamia.

More about zamia roezlii

About Zamia Roezlii

Zamia roezlii · also called Roezl's zamia, Colombian zamia · tropical

Zamia roezlii is a large tropical cycad from the wet lowland forests and swamps of Colombia and Ecuador, among the tallest-trunked of all Zamia. It carries long, leathery pinnate fronds atop a thick woody stem and wants warmth, humidity and steady moisture. Like all cycads it is highly toxic to pets from cycasin.

Cold limit: USDA 10-12 (tropical; indoor/greenhouse in temperate regions) · RHS H1b (20-32°C)

Watch for — Cold damage: Sensitive to chills below about 10°C; exposure browns or kills fronds. Keep it consistently warm and away from cold draughts and unheated rooms.

What zamia roezlii's hardiness rating actually means

Zamia Roezlii 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 (tropical; indoor/greenhouse in temperate regions) — 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). Zamia Roezlii has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Zamia Roezlii hardiness — frequently asked questions

Is zamia roezlii cold hardy?

Zamia Roezlii 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. Zamia Roezlii can only live outside year-round in genuinely frost-free climates (roughly USDA 10-12 (tropical; indoor/greenhouse in temperate regions)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature zamia roezlii can survive?

What hardiness zone is zamia roezlii?

Zamia Roezlii is rated USDA 10-12 (tropical; indoor/greenhouse in temperate regions) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can zamia roezlii 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 zamia roezlii 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.