Cold hardiness & minimum temperature

Is Rotala macrandra (Rotala macrandra)cold hardy? Hardiness zone & min temp

Also called giant red Rotala, broadleaf Rotala.

More about rotala macrandra

About Rotala macrandra

Rotala macrandra · also called giant red Rotala, broadleaf Rotala · tropical

A striking high-tech aquascaping stem plant with broad, ruffled leaves that turn deep pink to fiery red. More demanding than common rotalas, it needs strong light, stable CO2 and lean dosing to avoid stunting. A showpiece background or midground plant for experienced aquarists who can hold consistent water parameters.

Cold limit: USDA Not applicable (tropical aquarium plant grown indoors in heated water) (24-28°C)

What rotala macrandra's hardiness rating actually means

Rotala macrandra 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 Not applicable (tropical aquarium plant grown indoors in heated water) — 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). Rotala macrandra has no frost tolerance at all — it is an indoor plant in any climate with a real winter.

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

Rotala macrandra hardiness — frequently asked questions

Is rotala macrandra cold hardy?

Rotala macrandra 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. Rotala macrandra can only live outside year-round in genuinely frost-free climates (roughly USDA Not applicable (tropical aquarium plant grown indoors in heated water)); everywhere else it is a houseplant that summers out at most.

What is the minimum temperature rotala macrandra can survive?

What hardiness zone is rotala macrandra?

Rotala macrandra is rated USDA Not applicable (tropical aquarium plant grown indoors in heated water) and RHS H1b — Sub-tropical — a normal warm home is fine, but it cannot go outside in a cool season.

Can rotala macrandra 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 rotala macrandra 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.